Post by: jamonwindeyer on October 23, 2017, 11:38:07 am
I'll be writing a set of sample solutions to this exam, but don't take them as gospel - I'm not perfect! If you think something is off give a shout below and we'll see if something needs fixing.
Link to Exam: Click Here!
Current Solutions Status: First draft uploaded!! I've done a 3 hour exam in 1 hour and 22 minutes or so, so I've made mistakes. Guarantee it. Spot them and I will be forever in your debt ;D
Multiple Choice Solutions
(https://i.imgur.com/I6ctGEL.png)
(https://i.imgur.com/FHuPbIA.png)
(https://i.imgur.com/FHuPbIA.png)
Question 11 Solutions
(https://i.imgur.com/Ajf8Yr4.png)
(https://i.imgur.com/o8sad1w.png)
(https://i.imgur.com/o8sad1w.png)
Question 12 Solutions
(https://i.imgur.com/FtGhiKv.png)
(https://i.imgur.com/W8NAtcW.png)
(https://i.imgur.com/W8NAtcW.png)
Question 13 Solutions
(https://i.imgur.com/GeXRa5d.png)
(https://i.imgur.com/qxMC4fK.png)
(https://i.imgur.com/A9cADzp.png)
(https://i.imgur.com/qxMC4fK.png)
(https://i.imgur.com/A9cADzp.png)
Question 14 Solutions
(https://i.imgur.com/uPMO1fA.png)
(https://i.imgur.com/ZzTsqhX.png)
(https://i.imgur.com/M0Sc3dN.png)
(https://i.imgur.com/ZzTsqhX.png)
(https://i.imgur.com/M0Sc3dN.png)
Question 15 Solutions
(https://i.imgur.com/KfqeOlH.png)
(https://i.imgur.com/9EOkduD.png)
(https://i.imgur.com/5AiqDJJ.png)
(https://i.imgur.com/9EOkduD.png)
(https://i.imgur.com/5AiqDJJ.png)
Question 16 Solutions
(https://i.imgur.com/emBOYDB.png)
(https://i.imgur.com/uPQyz80.png)
(https://i.imgur.com/KWnQfo6.png)
(https://i.imgur.com/xrRwYI8.png)
(https://i.imgur.com/uPQyz80.png)
(https://i.imgur.com/KWnQfo6.png)
(https://i.imgur.com/xrRwYI8.png)
MY THOUGHTS
Brutal exam. I think it suited people who had done very specific forms of study, and those who are used to solving more challenging problems - MX1 students will likely flourish (at least a little) under the pressure, 2U students only - Whoa. This is a nasty one.
- The Multiple choice was okay, a trick in Q10 and a nicely challenging one at Q9.
- Stock standard in Q11 - That parabola question was interesting. Don't think I've seen it before, finding \(a\) was definitely not self apparent.
- Q12, also fine, though volume appearing so early was the first sign of trouble. Usually appears in Q14 or later - Gulp. What's coming?
- Q13 was the last reasonable one in my opinion, everything normal. Easy curve sketch. Lots of marks up for grabs here.
- Okay, so Q14 was alright. The Simpson's Rule question was cool, algebraic manipulation to use the estimation to find a value of \(\pi\). Nice little question, reasonable challenge. Stock standard exponential growth/decay question (easy 5 marks). The area between curves question was different, but the same method was expected as usual. Just finding an unknown in a different place, really.
- Q15, geometrical proof at the start was reasonable. The annuities question was ghastly - "We've run out of loan repayment and annuities questions!" "Okay, do BOTH AT THE SAME TIME LOLOLOL". Heh - Nasty stuff. But really, not too difficult, especially if you cleverly factorise. Motion question was on the upper end of difficulty, but should have been easy to interpret. No weird graphs or anything.
- Q16, just, wtf. Easily one of the weirdest/hardest questions we've had recently. I don't think my method of just brute force was what they anticipated, because I had done most of the work in (ii) for (iii) and (iv). Would be interested to see how you guys did it!
- Geometry question at the end was hard, for sure, but the very last part on angles was fine. Weird way to end a paper.
Overall, tough exam. Lots of weird questions, lots of difficult algebra, definitely harder than last year imo. If you studied the sorts of questions from the 2000's, this would have been an easier exam, because it felt like an exam out of the 2001-2005 era. But there you go - What did you think? :)
Post by: blasonduo on October 23, 2017, 05:32:49 pm
Post by: RuiAce on October 23, 2017, 05:34:00 pm
ohhhhhhhh boyyyyyyyyThat sounds a bit worrying :o
Post by: Dylpickle01 on October 23, 2017, 05:35:13 pm
Post by: Natasha.97 on October 23, 2017, 05:35:33 pm
Post by: RuiAce on October 23, 2017, 05:36:53 pm
Some q’s were deceptively hard :(Ewww... What made them deceptive?
Post by: Zamura1 on October 23, 2017, 05:37:11 pm
Post by: blasonduo on October 23, 2017, 05:37:22 pm
That sounds a bit worrying :o
It was just the last question, everything else was pretty okay, I don't think I did many mistakes, but geometry proofs are my weakness, and part of 16 was geometry :( I think I got 3/15 for 16, which REALLY bothers me :/ )
Post by: Anything on October 23, 2017, 05:40:35 pm
Post by: RuiAce on October 23, 2017, 05:40:46 pm
It was just the last question, everything else was pretty okay, I don't think I did many mistakes, but geometry proofs are my weakness, and part of 16 was geometry :( I think I got 3/15 for 16, which REALLY bothers me :/ )Ouch!
That is gonna bug a lot of people
Post by: lcamilleri.53 on October 23, 2017, 05:41:12 pm
Post by: RuiAce on October 23, 2017, 05:41:54 pm
Am I the only one who struggled more with the last 2 bicycle questions than the geometry ones?Well I mean, everyone has their different strengths and weaknesses so you shouldn't worry if you're the one "here" that does. (Besides it's kinda unlikely that you were; others probably haven't come on the forums yet)
Post by: Natasha.97 on October 23, 2017, 05:44:12 pm
Ewww... What made them deceptive?
There was this arithmetic and geometric sequences q that I couldn’t get for ages, had to cross out my working out multiple times >:( got it in the ens though :3 also the geometry proofs... :(
Post by: blasonduo on October 23, 2017, 05:46:20 pm
Also, for some questions (such as that t^1/2 + t^2/3 - 6 = 0) I just put the answers, with no working out (i'm 100% sure they are right) I should get full marks right?
Post by: RuiAce on October 23, 2017, 05:46:35 pm
There was this arithmetic and geometric sequences q that I couldn’t get for ages, had to cross out my working out multiple times >:( got it in the ens though :3 also the geometry proofs... :(Wait there was a fucked up series this year??
The proof for the bike was dead simple, the other parts, not so much.That outta depend on the question itself and what it asked you to do.
Also, for some questions (such as that t^1/2 + t^2/3 - 6 = 0) I just put the answers, with no working out (i'm 100% sure they are right) I should get full marks right?
Jamon might be able to give you insight on it later if you ask it again, since he's writing up your solutions
Post by: Anything on October 23, 2017, 05:48:00 pm
Wait there was a fucked up series this year??
Perhaps referring to the question that asked for values of a to make a limiting sum = 2 where a is the first term
Post by: Opengangs on October 23, 2017, 05:48:19 pm
everything else felt pretty easy, I bs'ed the iso proof tho.
Post by: Dylpickle01 on October 23, 2017, 05:50:33 pm
I bs'ed the iso proof tho.
Same
Did anyone manage to get the x value for the bicycles?
Post by: RuiAce on October 23, 2017, 05:51:18 pm
Perhaps referring to the question that asked for values of a to make a limiting sum = 2 where a is the first termLol that's new.
Post by: Anything on October 23, 2017, 05:51:52 pm
Lol that's new.
They didn't give any values, aside from the limiting sum having to equal 2
Post by: Dylpickle01 on October 23, 2017, 05:52:04 pm
Lol that's new.Weren't given r either
Post by: itsAnuu on October 23, 2017, 05:52:21 pm
Post by: RuiAce on October 23, 2017, 05:52:49 pm
Post by: Opengangs on October 23, 2017, 05:54:26 pm
They didn't give any values, aside from the limiting sum having to equal 2Use the fact that |r| < 1 for a limiting sum to exist
a/(1 - r) = 2
a = 2(1 - r)
Now, -1 < r < 1
1 > -r > -1
2 > 1 - r > 0
4 > a > 0
Post by: itsAnuu on October 23, 2017, 05:55:07 pm
Use the fact that |r| < 1 for a limiting sum to exist
yeh easy q
Post by: 1MARIE1 on October 23, 2017, 05:56:10 pm
yeh easy qWasn't it worth like 3 marks? or was it 2?
Post by: RuiAce on October 23, 2017, 05:57:58 pm
Use the fact that |r| < 1 for a limiting sum to existAhh right. After I saw what was above I instantly questioned if it had to do with the |r|<1 scenario.
a/(1 - r) = 2
a = 2(1 - r)
Now, -1 < r < 1
1 > -r > -1
2 > 1 - r > 0
4 > a > 0
Still though, I want to see the exact wording of this Q...
Post by: RuiAce on October 23, 2017, 05:58:55 pm
yeh easy qIt's honestly so hard to call a question easy these days. Especially for some people in the middle of the actual exam.
Because whereas the computations can be fairly simple, trying to get that moment of inspiration to getting started isn't so simple for some.
Post by: ellybubble on October 23, 2017, 05:59:43 pm
Wasn't it worth like 3 marks? or was it 2?i think it was worth 3 marks, so quite alot
Post by: Zainbow on October 23, 2017, 05:59:56 pm
Post by: taylorlucy on October 23, 2017, 06:00:29 pm
Wasn't it worth like 3 marks? or was it 2?
Yep that was worth 3 marks! Thought I must be doing something wrong considering I only had a few lines of working and it was in Q16, but I got 0<a<4 too! Perhaps there was a trick I missed, but I hope not!
Post by: adelaidecruz on October 23, 2017, 06:03:40 pm
Post by: 1MARIE1 on October 23, 2017, 06:05:35 pm
Did anyone else find the loan repayment question confusing??
Yeah, it was kind of weird. It took me ages to get to the answer for the second part
Post by: sajochi on October 23, 2017, 06:06:29 pm
Did anyone else find the loan repayment question confusing??
At first, yes. I thought she only deposited one initial sum of X so money was only withdrawn and thus I couldn't match the required result, but I came back to it later and realised she deposited $X per month and managed to get it out.
Post by: georgiia on October 23, 2017, 06:07:10 pm
Ahh right. After I saw what was above I instantly questioned if it had to do with the |r|<1 scenario.
Still though, I want to see the exact wording of this Q...
How many of the 3 marks could I potentially get for getting to this line of working:
a= 2(1-r) , -1<r>1
?
Thanks!
Post by: georgiia on October 23, 2017, 06:10:20 pm
At first, yes. I thought she only deposited one initial sum of X so money was only withdrawn and thus I couldn't match the required result, but I came back to it later and realised she deposited $X per month and managed to get it out.Did anyone get something around $4608 or something like that for that question?
(The value of X)
Post by: Zainbow on October 23, 2017, 06:11:35 pm
Did anyone get something around $4608 or something like that for that question?
(The value of X)
That seems similar to what I got
Post by: sajochi on October 23, 2017, 06:11:52 pm
How many of the 3 marks could I potentially get for getting to this line of working:
a= 2(1-r) , -1<r>1
?
Thanks!
I'm not sure sorry, I'd say one or possibly two. I could be wrong but I think the best way to show it was using limits as r approaches 1 and -1 (by considering both solutions of | r | < 1 )
Post by: RuiAce on October 23, 2017, 06:13:05 pm
How many of the 3 marks could I potentially get for getting to this line of working:It's a bit unclear what you're trying to argue I'm afraid. I'd probably have only given that 1 :(
a= 2(1-r) , -1<r>1
?
Thanks!
Post by: bimberfairy on October 23, 2017, 06:13:14 pm
Post by: 12070 on October 23, 2017, 06:13:39 pm
Post by: bimberfairy on October 23, 2017, 06:14:11 pm
Did anyone get something around $4608 or something like that for that question?
(The value of X)
I got $4019 for it?? And i forgot the amount of cents that i rounded to LOL
Post by: caitlinlddouglas on October 23, 2017, 06:14:25 pm
SameI got x = 3.75
Did anyone manage to get the x value for the bicycles?
Post by: K9810 on October 23, 2017, 06:14:55 pm
Post by: bimberfairy on October 23, 2017, 06:15:22 pm
So annoyed with question 16. Could only do the limiting sum question and like two marks of a. Probably got 5/15 when I was getting around 8-12 in other papers. Also with the loan repayment, I had two series going. Was that right or did I just make up some Maths? (Probably the latter)
There should’ve been two series happening at the same time! One attached to X and one attached to the loan repayment subtracted.
Post by: sajochi on October 23, 2017, 06:15:33 pm
Surprisingly, i was able to do the geometry questions of question 16 but struggled so much with the last two parts of the bicycle question. Somehow i got x=90 LOOOOOL
Same for the geometry! After ALOT of time spent trying things... Thankfully my friend had reminded me of the ratio of intercepts theory only a few days ago!
So annoyed with question 16. Could only do the limiting sum question and like two marks of a. Probably got 5/15 when I was getting around 8-12 in other papers. Also with the loan repayment, I had two series going. Was that right or did I just make up some Maths? (Probably the latter)
Hahaha, don't worry, there were meant to be two!
Post by: doyouevencheeto on October 23, 2017, 06:16:08 pm
Post by: caitlinlddouglas on October 23, 2017, 06:16:37 pm
Use the fact that |r| < 1 for a limiting sum to existahhh far out I got that answer but made my answer a<4!!! Would they award the other marks though?
a/(1 - r) = 2
a = 2(1 - r)
Now, -1 < r < 1
1 > -r > -1
2 > 1 - r > 0
4 > a > 0
Post by: RuiAce on October 23, 2017, 06:17:45 pm
Won't address its difficulty nor will I post any solutions (for 2U that's Jamon's job). The questions certainly look manageable but they just...look so weird...
Can someone please upload the exam paper? I don't care if it's just photos but I want to have a go at it hahaI'm afraid we cannot. Copyright issues.
Post by: georgiia on October 23, 2017, 06:17:52 pm
It's a bit unclear what you're trying to argue I'm afraid. I'd probably have only given that 1 :(no that was only the last line of working
Post by: ellybubble on October 23, 2017, 06:18:24 pm
Did anyone get that part in Q16 about the isosceles triangle? I was so confused :(
I think you had to use the ratio of intercepts on parallel lines to prove that the two sides were equal?
Post by: sajochi on October 23, 2017, 06:18:40 pm
I think you had to use the ratio of intercepts on parallel lines to prove that the two sides were equal?
Yeah that's what I used
Post by: doyouevencheeto on October 23, 2017, 06:19:31 pm
Just saw your paper. Geez some of the stuff looks weird.
Won't address its difficulty nor will I post any solutions (for 2U that's Jamon's job). The questions certainly look manageable but they just...look so weird...
I'm afraid we cannot. Copyright issues.
When do you think the paper will be released for viewing on this?
Post by: ellybubble on October 23, 2017, 06:20:14 pm
Did anyone else find the loan repayment question confusing??
yep, and i'm pretty sure I did it wrong now hahah
Post by: 12070 on October 23, 2017, 06:21:43 pm
There should’ve been two series happening at the same time! One attached to X and one attached to the loan repayment subtracted.
Yeah okay sweet. I remember I got 4000 and something but will have to wait for the solutions to see if I got it. Also for the series one where you had to find t10, I found a1 by trial and error but I did get the correct answer I think t10=0. However, would I still get the 3 marks for using trial and error?
Post by: lcamilleri.53 on October 23, 2017, 06:21:52 pm
Post by: RuiAce on October 23, 2017, 06:22:10 pm
no that was only the last line of workingYou might be lucky to get a 2 then. You should easily have secured 1 mark just for using the GP sum formula.
Can't promise you the second though
NESA has been relatively fast this year. Hopefully within the next 2-3 days.
When do you think the paper will be released for viewing on this?
Post by: bimberfairy on October 23, 2017, 06:24:32 pm
Yeah okay sweet. I remember I got 4000 and something but will have to wait for the solutions to see if I got it. Also for the series one where you had to find t10, I found a1 by trial and error but I did get the correct answer I think t10=0. However, would I still get the 3 marks for using trial and error?
Yeah i got t10 = 0 too. You’d definitely get a mark for getting the answer. I’m not too sure about the trial and error method though because i think they intended for you to figure out t4 and the sum then use simultaneous equations.
Post by: RuiAce on October 23, 2017, 06:27:54 pm
Post by: navtejkr on October 23, 2017, 06:30:04 pm
That seems similar to what I gotYES I THINK I GOT THAT TOO
Post by: Anything on October 23, 2017, 06:32:10 pm
Q11-14 seemed pretty straightforward yeah?
Yeah pretty much only Q15 and Q16 were a hassle
Post by: portia1605 on October 23, 2017, 06:35:47 pm
Post by: adelaidecruz on October 23, 2017, 06:38:12 pm
so what did people get for the second part of the finance question. i got 88000 originally then redid it and got 4019, then subbed that back in and it didnt work and then got something like 4021 or something ???Aaah forgot everything the minute I stepped out of the school but my answer was around ~4000 too!
Post by: Annie657 on October 23, 2017, 06:39:01 pm
I got $4019 for it?? And i forgot the amount of cents that i rounded to LOL
Me too! Hah I think it was right lol
Post by: georgiia on October 23, 2017, 06:40:30 pm
Post by: K9810 on October 23, 2017, 06:41:13 pm
Post by: navtejkr on October 23, 2017, 06:41:56 pm
do you think i could still get marks for using simultaneous equations tho?
Post by: Anfar3 on October 23, 2017, 06:43:11 pm
Post by: Opengangs on October 23, 2017, 06:44:07 pm
How did everyone go for that question where we had to integrate cosx using Simpsons rule between 0 and pi/3? What did you get??Easy, since it was one application, use the formula from the formula sheet.
Can't remember the exact value, tho
For the find the 10th term question, i used simultaneous equations for the 5th term and the sum of the first 4 terms and whatever they gave in the question but i swear it didnt make sense in the end. Idk what i did wrong cs the difference was -40 and my first term was 40, and it just didnt add up and now i feel shit and scared about that questiondifference was -40, but the first term should have been 360
do you think i could still get marks for using simultaneous equations tho?
Post by: Sahana2 on October 23, 2017, 06:44:10 pm
Did anyone get something around $4608 or something like that for that question?
(The value of X)
yeah i think i got that aswell
Post by: georgiia on October 23, 2017, 06:44:18 pm
For the find the 10th term question, i used simultaneous equations for the 5th term and the sum of the first 4 terms and whatever they gave in the question but i swear it didnt make sense in the end. Idk what i did wrong cs the difference was -40 and my first term was 40, and it just didnt add up and now i feel shit and scared about that question
do you think i could still get marks for using simultaneous equations tho?
I'm pretty sure i got -40 for the difference but 0 for the answer
Post by: adelaidecruz on October 23, 2017, 06:44:43 pm
For the find the 10th term question, i used simultaneous equations for the 5th term and the sum of the first 4 terms and whatever they gave in the question but i swear it didnt make sense in the end. Idk what i did wrong cs the difference was -40 and my first term was 40, and it just didnt add up and now i feel shit and scared about that question
do you think i could still get marks for using simultaneous equations tho?
I used simultaneous equations too for T5 and S4 and I got -40 as my d. As long as you got 0 for the 10th term you're all good :D
Post by: _____ on October 23, 2017, 06:45:08 pm
Post by: RuiAce on October 23, 2017, 06:45:29 pm
B6 raw? I found it harder than 2016 and 15 so maybe around 83?I do anticipate that there will be heavier alignment since a lot of candidates found it hard. If it's usually 85 or so then 83 this year is probably a fair call
Post by: Opengangs on October 23, 2017, 06:47:07 pm
What did people get for the congruent triangles thing? I got x = 45 degrees but I'm not too sure (using tan and drawing new right angled triangles).Wasn't it 36 degrees?
Post by: bimberfairy on October 23, 2017, 06:47:09 pm
What did people get for the congruent triangles thing? I got x = 45 degrees but I'm not too sure (using tan and drawing new right angled triangles).
I got x= 36 degrees ? Was this the one with three congruent triangles? And the parallel lines? Because i used matching angles of congruent triangles are equal then co-interior angles on parallel lines.
Post by: bimberfairy on October 23, 2017, 06:48:19 pm
Wasn't it 36 degrees?
Yeah i got 36 degrees
Post by: lcamilleri.53 on October 23, 2017, 06:49:07 pm
Post by: banway on October 23, 2017, 06:49:44 pm
Seems like many people were the same.
I'll be keen to see the working and paper again to have at it to see what was needed to be done
Post by: Dylpickle01 on October 23, 2017, 06:50:05 pm
Post by: RuiAce on October 23, 2017, 06:50:13 pm
Post by: jamonwindeyer on October 23, 2017, 06:50:18 pm
Post by: _____ on October 23, 2017, 06:50:24 pm
Yeah i got 36 degrees
RIP I used the wrong method
Post by: georgiia on October 23, 2017, 06:50:49 pm
What did people get for the congruent triangles thing? I got x = 45 degrees but I'm not too sure (using tan and drawing new right angled triangles).
I may be wrong but i think i got 36. I sort of approached it the cheating way by 'assuming' the lines were parallel and showing that by alternate angles it would've been twice the size of the base angles. I'm not sure if that was the correct way to work it out though...
Post by: RuiAce on October 23, 2017, 06:52:05 pm
I may be wrong but i think i got 36. I sort of approached it the cheating way by 'assuming' the lines were parallel and showing that by alternate angles it would've been twice the size of the base angles. I'm not sure if that was the correct way to work it out though...Judging by that wording you were meant to assume that they were parallel
Post by: bimberfairy on October 23, 2017, 06:52:33 pm
What was everyone's thoughts of the multiple choice. I think i changed the locus one from the correct answer when I went back through the exam
I thought multiple choice was pretty good this year!!! I had a hard time with question 9, and did alot of substitution and fiddling around. For the locus, i got it as a circle?
Post by: Zainbow on October 23, 2017, 06:52:38 pm
I do anticipate that there will be heavier alignment since a lot of candidates found it hard. If it's usually 85 or so then 83 this year is probably a fair call
Best thing I heard all day, I came out of the exam not feeling very confident so I really hope this is true
Post by: herb123 on October 23, 2017, 06:53:20 pm
Post by: Dylpickle01 on October 23, 2017, 06:53:21 pm
Ok so question 16 really screwed me over. I, not to sound confident, felt on track to nearly ace the test assuming I made no silly errors the rest of the way through. Then 16 came and with the hour I had to spare it choked me and stumped me entirely.
Seems like many people were the same.
I'll be keen to see the working and paper again to have at it to see what was needed to be done
Me too! I felt pretty good with the rest of the paper, then 16 struck. It'll be interesting to see how marks are aligned and moderated considering how most of the cohort felt about it
Post by: georgiia on October 23, 2017, 06:54:39 pm
Judging by that wording you were meant to assume that they were parallel
Post by: georgiia on October 23, 2017, 06:55:18 pm
I thought multiple choice was pretty good this year!!! I had a hard time with question 9, and did alot of substitution and fiddling around. For the locus, i got it as a circle?
Oh no i got parabola :0
Post by: RuiAce on October 23, 2017, 06:55:33 pm
Maybe i assumed they were isosceles or something that they said prove and i wrote "assuming ----" then proved itYou were meant to assume that as well lol
Edit: Well, maybe assume is a bad word. But it's a one line proof to show that they're isosceles triangles due to all the equal sides they give you.
last years raw for band 6 was 82Well in that case this year might go down to 81 (or with enough luck 80)
Post by: _____ on October 23, 2017, 06:56:59 pm
Oh no i got parabola :0
Same
Post by: RuiAce on October 23, 2017, 06:58:36 pm
"always equidistant from two fixed points"
Post by: lcamilleri.53 on October 23, 2017, 06:58:37 pm
Post by: JoyMaalouf on October 23, 2017, 06:59:10 pm
is all I have to say
Post by: Annie657 on October 23, 2017, 07:00:56 pm
If this is the multiple choice question I think the locus is a straight line.
"always equidistant from two fixed points"
Yay yay yay
Post by: bimberfairy on October 23, 2017, 07:02:06 pm
If this is the multiple choice question I think the locus is a straight line.
"always equidistant from two fixed points"
Yeah i think it was a straight line too. Far out, i put circle LOL
Post by: banway on October 23, 2017, 07:02:12 pm
Well in that case this year might go down to 81 (or with enough luck 80)
Well that's not too bad I guess, I'd be pretty happy with an 81, I think even going off the 82 of last year I'm feeling comfortable with that for a band 6, I'll be the bottom of the barrel but I'm cool with that
Post by: RuiAce on October 23, 2017, 07:03:07 pm
Fixed distance from one single point - circle
Equidistant from two points - straight line
Equidistant from point and line - parabola
Well that's not too bad I guess, I'd be pretty happy with an 81, I think even going off the 82 of last year I'm feeling comfortable with that for a band 6, I'll be the bottom of the barrel but I'm cool with thatWell a band 6 is a band 6. Here's to hoping alignment will stay fair
Post by: banway on October 23, 2017, 07:04:13 pm
Yeah i think it was a straight line too. Far out, i put circle LOL
Yeah I ended up answering that it was a straight line. All the rest either used a point and a line, or a point and the other point wasn't fixed. So I said Straight line
Post by: adelaidecruz on October 23, 2017, 07:05:03 pm
Rip sorry to break it to you guys
Fixed distance from one single point - circle
Equidistant from two points - straight line
Equidistant from point and line - parabolaWell a band 6 is a band 6. Here's to hoping alignment will stay fair
Far out I changed my answer from straight line to circle :/
Post by: bimberfairy on October 23, 2017, 07:05:55 pm
Yeah I ended up answering that it was a straight line. All the rest either used a point and a line, or a point and the other point wasn't fixed. So I said Straight line
I should’ve drawn it out or something. Because i basically visualised the whole thing in my mind and who even knows what graph i concocted 😂😂😂
Post by: Cecette on October 23, 2017, 07:06:35 pm
Post by: RuiAce on October 23, 2017, 07:07:28 pm
hey, is anyone else having trouble viewing the suggested solutions? The drop down isn't working.... ripThey're not uploaded yet; Jamon is still in the process of writing and/or scanning them
Post by: Cecette on October 23, 2017, 07:08:55 pm
They're not uploaded yet; Jamon is still in the process of writing and/or scanning themOH RIGHT THAT MAKES SO MUCH SENSE thank you :D
Post by: blasonduo on October 23, 2017, 07:13:20 pm
Post by: malachiyoung on October 23, 2017, 07:14:20 pm
Post by: mary123987 on October 23, 2017, 07:20:59 pm
PERSONALLY I DONT THINK IT WAS THAT HARD BUT IT WAS ALOT TO DO IN THE 3 HOURS idk i think i went okay
Post by: Anything on October 23, 2017, 07:24:24 pm
DOES ANYONE ELSE FEEL OVERLY TIRED ? HONESTLY THE MORE I CHECK OR THINK BOUT THE ANSWERS THE MORE I FEEL LIKE CRAP :'( :'( :'( :'( :'( :'( :'( :'( :'( :'( :'( :'( :'( :'( :'( :'( :'( :'( :'( I FEEL REALLY DOWN :(
PERSONALLY I DONT THINK IT WAS THAT HARD BUT IT WAS ALOT TO DO IN THE 3 HOURS idk i think i went okay
The test is done I'm sure you gave it your best shot, there's no point worrying about what has already been completed but instead focus on peaking for the rest of your exams
Post by: janemurray on October 23, 2017, 07:24:54 pm
I do anticipate that there will be heavier alignment since a lot of candidates found it hard. If it's usually 85 or so then 83 this year is probably a fair call
Sorry this is probably a stupid question but how do the bands work? I thought the band 6 cut off was 90? and band 5 was 80 etc.
Post by: mary123987 on October 23, 2017, 07:26:29 pm
The test is done I'm sure you gave it your best shot, there's no point worrying about what has already been completed but instead focus on peaking for the rest of your examsDefinitely agree man !!! It is what it is hopefully i smash the rest !!
Post by: doyouevencheeto on October 23, 2017, 07:31:21 pm
Sorry this is probably a stupid question but how do the bands work? I thought the band 6 cut off was 90? and band 5 was 80 etc.
Yes you are correct however I believe there is a discrepancy in your understanding of what the others are talking about. The marks you receive on the 15th December (I think it's 15th) is your aligned mark (if you get a 90+ aligned mark, you get a b6). This is different to your raw mark (the actual mark you get /100). Once NESA have marked all exams, if they believe the exam was too hard, they'll align it accordingly so that the final mark is fair. Hope this helps!
http://rawmarks.info/wiki/Mathematics
Have a look at this btw, it'll help you understand it more
Post by: sajochi on October 23, 2017, 07:31:27 pm
Sorry this is probably a stupid question but how do the bands work? I thought the band 6 cut off was 90? and band 5 was 80 etc.
They're the aligned cut-offs yes... But dependent on how everyone performs within your cohort, raw marks are 'aligned' either up or down to best produce a bell curve. Hence a raw mark of around 85 often is aligned upward above 90 and you receive a band 6.
Post by: inescelic on October 23, 2017, 07:32:36 pm
Post by: taylorlucy on October 23, 2017, 07:34:59 pm
Post by: dannimoussa on October 23, 2017, 07:39:33 pm
Also, for last a part of question 11, did they also ask for range? i thought it was just domain
Post by: jamonwindeyer on October 23, 2017, 07:40:35 pm
An insignificant mistake but in 12b) the volume needs a pi in it. Thanks for the solutions Jamon!
Thank you for the spot! Will fix that!
As implied, first draft is up!! Keen to have lots of mistakes fixed - I've also put some of my thoughts on the exam in the OP ;D
Post by: ang3244 on October 23, 2017, 07:40:50 pm
D;
Post by: Guss123 on October 23, 2017, 07:41:13 pm
Post by: Anything on October 23, 2017, 07:42:30 pm
(as a shorter method)
Post by: con_fisher on October 23, 2017, 07:44:12 pm
Post by: Rosie52273 on October 23, 2017, 07:44:42 pm
Post by: inescelic on October 23, 2017, 07:45:13 pm
For 16ci, did anyone else use "line joining the midpoints of two sides of a triangle is parallel to and equal to half of the third side?" i didn't need to prove similarity and im worried that my proof isn't valid as a result???I did the same thing... like transversals on parallel lines are in the same ratio?
D;
Post by: herb123 on October 23, 2017, 07:47:20 pm
Post by: jamonwindeyer on October 23, 2017, 07:48:29 pm
For 16ci, did anyone else use "line joining the midpoints of two sides of a triangle is parallel to and equal to half of the third side?" i didn't need to prove similarity and im worried that my proof isn't valid as a result???
D;
I don't think that's a quotable result unfortunately :(
Hey, for 16.a)ii) You were meant to differentiate, which gave you the trigonometric values of the triangle. You were not meant to solve for x yet. e.g. sin(alpha) = x/root(25+x^2) and sin(beta) = (9-x)/root(49+(9-x)^2 which gives you 0 = sin(alpha) - sin (beta), so sin(alpha) = sin(beta)
Hey Jamon, with the dL/dx = 0 question, you could have subbed in sin(alpha) and sin(beta), using the trig identity (right angled triangle). Albeit maintaining the factorised form
(as a shorter method)
Ahh, clever! I just jumped straight into the brute force since I was in a rush ;)
My method would definitely still be worth full marks, but definitely isn't as efficient as you guys, good stuff on spotting it!! ;D
you forgot the pii in 12 b :)
Welcome to the forums! That should be fixed now if you look again ;D
I did the same thing... like transversals on parallel lines are in the same ratio?
That is a quotable result ;D
Post by: navtejkr on October 23, 2017, 07:50:31 pm
Post by: con_fisher on October 23, 2017, 07:50:44 pm
Post by: goodguy on October 23, 2017, 07:50:50 pm
Post by: portia1605 on October 23, 2017, 07:53:27 pm
Post by: FirKangaroo on October 23, 2017, 07:54:08 pm
Post by: ang3244 on October 23, 2017, 07:55:06 pm
I did the same thing... like transversals on parallel lines are in the same ratio?
I'm worried because my proof was literally:
In triangle BEC:
D bisects BE (line [MD] joining midpoints of two sides [BE and MC] is parallel to and equal to half the length of the third side [CE])
∴ BD = DE
∴ DE = DA + AC
and since DE = DA + AE as well,
AC = AE ∴ isoceles triangle
And I don't know if the midpoint thing was a correct assumption (like got the answer but will I lose marks for working)?
Post by: Anything on October 23, 2017, 07:57:33 pm
I dont understand how with the last multiple choice question , the direction changes only once? i thought it was 3 times ?The question illustrated a velocity graph and we know direction changes when the sign of velocity changes from positive to negative or negative to positive, since the graph crossed the x axis, only once it changed direction only once.
Post by: banway on October 23, 2017, 07:57:37 pm
Hey guys, I'm new to the forum. Where is everyone getting the solutions to the 2u exam? Could anyone link me please ?
Jump back to page one and there are expandable spoilers
Also just wondering, I'm probably being a bit paranoid, but how much do they care about the setting out of the working? I'm worried mine might have been too crammed onto the pages even where I spilled into another book. As long as I've underlined all the answers and my writing is legible I should be ok yeah? Also is on the smaller side handwriting still alright cus my writing isn't huge scrawl, like half of the 10mm lines they give so like 5mm :o
Post by: mbdtHSC on October 23, 2017, 07:58:38 pm
Post by: basz on October 23, 2017, 07:59:24 pm
Post by: georgeharb27 on October 23, 2017, 08:00:07 pm
Post by: ZihanZhao on October 23, 2017, 08:00:12 pm
Post by: sangok on October 23, 2017, 08:00:20 pm
Post by: ang3244 on October 23, 2017, 08:01:00 pm
should be all good
Post by: navtejkr on October 23, 2017, 08:02:56 pm
would that maybe be a band 6?
Post by: doyouevencheeto on October 23, 2017, 08:05:17 pm
according to your solutions, i got a raw 85/86
would that maybe be a band 6?
I haven't seen the exam but by reading responses to the exam I'm assuming you'd comfortably fit into a b6
Post by: Anfar3 on October 23, 2017, 08:06:09 pm
Post by: Opengangs on October 23, 2017, 08:09:45 pm
Post by: mbdtHSC on October 23, 2017, 08:11:20 pm
Based on the exam solution, I'm looking at around 95-96 raw.
same, what do you think that'll end up as for external mark?
Post by: broxy11 on October 23, 2017, 08:12:38 pm
Post by: adelaidecruz on October 23, 2017, 08:21:26 pm
Post by: Merin Thomas on October 23, 2017, 08:22:26 pm
Post by: georgiia on October 23, 2017, 08:23:17 pm
Post by: doyouevencheeto on October 23, 2017, 08:29:58 pm
Post by: navtejkr on October 23, 2017, 08:31:10 pm
anyone else?
Post by: winstondarmawan on October 23, 2017, 08:32:56 pm
Post by: bimberfairy on October 23, 2017, 08:36:08 pm
For the limiting series question, wouldn't there need to be a=/=1,2?
I don't believe there should be ? Can I ask how you got that conclusion?
Post by: bimberfairy on October 23, 2017, 08:39:48 pm
The AP and GP question using simultaneous questions... clever but cheeky nesa
I've never come across a question like that before in the past papers so it shook me for a bit hahaha will have to agree that it was really clever!
Post by: georgiia on October 23, 2017, 08:40:39 pm
btw what ATARs are you guys going for and what course do you want to do next year?
Atar: >94
and I want to do film :) 🎬
Post by: jay24495 on October 23, 2017, 08:46:49 pm
Post by: Janey123 on October 23, 2017, 08:48:29 pm
Post by: sidzeman on October 23, 2017, 08:48:57 pm
Post by: dory1866 on October 23, 2017, 08:50:52 pm
re your solution regarding question 16 aii, in which you needed to find x, I found it easier to prove similarity of triangles ace and the other one (equiangular if sina=sinb), then just use ration of sides to find x. came out as 5/7=x/9-x and then solve. less opportunity for calculator mis-entry for the quad formula.
Post by: OliverN on October 23, 2017, 09:14:15 pm
Post by: caprese_ on October 23, 2017, 10:09:29 pm
Post by: BOBBY13579 on October 23, 2017, 10:28:27 pm
Post by: wilko224 on October 23, 2017, 10:31:00 pm
Post by: jamonwindeyer on October 23, 2017, 10:33:46 pm
Hey, in this do we have to specify that a =/= 2 ? Because if r = 0 then a = 2, but do we have to specify that r =/= 0 ? Thank you
Hey! I discussed this with friends and I think that, since the definition is \(|r|<1\), \(r=0\) is technically an allowable value. The series would be 2+0+0+0...
It is weird but I think allowable! :)
For the 2 significant figures question shouldn't the answer be 870, considering you use the proper k value? not the approximation, also last question of 11 shouldn't the range be cut off to root 3
The sig figs question is definitely 880, it is standard practice to use the rounded value if it is given to you (they would probably pay you if you used the actual value too though) ;D
The range of that function is infinite, if \(x\) is a large negative value you can get large positive values out ;D
what do you think you would need for a state rank? 99?
Always need 99 or 100 raw, you might scrape in with a 98 this year but usually people are able to get pretty high marks in these exams - I think, at least ;D
What do you think 95 raw would become
High 90's :)
Jump back to page one and there are expandable spoilers
Also just wondering, I'm probably being a bit paranoid, but how much do they care about the setting out of the working? I'm worried mine might have been too crammed onto the pages even where I spilled into another book. As long as I've underlined all the answers and my writing is legible I should be ok yeah? Also is on the smaller side handwriting still alright cus my writing isn't huge scrawl, like half of the 10mm lines they give so like 5mm :o
Underlining your answers will definitely help you, if that underlined answer is correct then they are likely not to pay much attention to the rest (unless it is a proof) - I'm sure you will be fine ;D
Post by: jamonwindeyer on October 23, 2017, 10:38:04 pm
Would you be able to post up a copy of the exam?
The exam will be posted by NESA very soon, we aren't hosting them ourselves anymore ;D
Jamon how do you reckon this test compares to the one in 2013
From vague memory, this is a harder exam!
Based on the exam solution, I'm looking at around 95-96 raw.
Should align to high 90's ;D
Am I the only one who used similar triangles to solve X in question 16
I'm not sure if it was possible to do it that way! If you post your solution I can let you know what I'd score it? ;D
For questions 16ci, can u use the midpoint theorem of the triangle? and say BD = DA + AE and its given that BD = DA + AC~ cause i didnt prove that it was simlar triangle and stuff. ~ but i rather stated the mid point formulae theorem ~ WILL THAT BE FINE?
A lot of people seem to have used this result, and I'm not sure - I don't think it is a quotable result but I could be wrong!
I got this answer but accidentally forgot that t> 0 so even though i had the exact last line Jamon has, will i loose a mark for writing that t=0 is a solution?
I reckon you might get off the hook for that - It's such an inconsequential part of the question they might not actually care ;D
Post by: avalansh7 on October 23, 2017, 10:42:22 pm
Post by: bimberfairy on October 23, 2017, 10:50:55 pm
Hey,
I just sat the exam today and got pretty much the same answers. I really hope 11h was only asking for domain :-\ and that financial was a bit tricky though i got it in the end. My classmates are questioning Q16c for the limiting sum=2 question. Most of us got 0<a<4, but since it is a GP half of us are questioning whether r=0 is possible and hence a=2 is a solution within this range. So could it perhaps be 0<a<4, a is not equal to 2, or is it just 0<a<4. I put 0<a<4.
If the domain question you're referring to was the one with x in the square root, then yes, i'm very sure it was asking for domain only!
Post by: jamonwindeyer on October 23, 2017, 10:52:23 pm
tbh for that area under the curve question, i got k = -2.5
anyone else?
What was your method? I may have screwed up ;D
Is it fine is I used transversals as my reasoning for that isosceles proving question....BM/MC = BD/DE....then i did the arranging of the equestion they gave and the one I made which was i think same as urs....
I think that sounds alright! :)
Anyone have any guesses for the raw marks for band allocations this year? For band 5?
I reckon they'll be semi-low this year. 2013's B6 cutoff was about 77, I reckon this could be similar, maybe even 75 or so. B5 cut-off maybe very low 70's?
If we did the questions out of order would that affect our marks in anyway? For example for the cycling question I did part ii in my extra writing book and not before part iii
Provided they can find everything you'll be fine ;D
Hey mate,
re your solution regarding question 16 aii, in which you needed to find x, I found it easier to prove similarity of triangles ace and the other one (equiangular if sina=sinb), then just use ration of sides to find x. came out as 5/7=x/9-x and then solve. less opportunity for calculator mis-entry for the quad formula.
Definitely a way better method my friend!! Brute force was pretty ugly hey ;)
The question about the three isosceles triangles (15A) the common answer is 36deg but did anyone else also get 108deg as an answer for obtuse-angled triangles? I am fairly sure there are two answers but curious what the general consensus on this is and if NESA is likely to recognise both answers.
I don't think that could be possible since you need to fit three of the angles, plus an extra, into 180 degrees for them to be parallel right? Could you perhaps elaborate further? :)
for the kangaroo question, i got 870 because i used the unrounded answer of k . i gave the final answer in 2sf. do you think i will still get the mark? :(
I reckon you should! :)
what do you guys think the raw mark for state rank would be for this test?
Still 99 or 100 I think :)
If the domain question you're referring to was the one with x in the square root, then yes, i'm very sure it was asking for domain only!
Confirming it was - I've only just realised I added the work for myself! ;D
Post by: amberberrie on October 23, 2017, 10:53:11 pm
Post by: alihkhan8 on October 23, 2017, 10:53:59 pm
Any chance of me getting a band 6 or have I fked it?
Post by: liya1234 on October 23, 2017, 10:55:17 pm
Post by: jamonwindeyer on October 23, 2017, 10:58:06 pm
Raw mark for band 6??
High 70's I reckon is a safe bet, it could be as low as like 75 at a stretch ;D
So I got 83/100 for this exam. My school rank is 11/190 and last year around 50 people at my school got band 6.
Any chance of me getting a band 6 or have I fked it?
Pretty likely you'll get a B6 I'd wager my friend - Congrats on a great score in a tough exam ;D
thank you so much for getting these up for us!!! i really appreciate it xx
Very welcome! I enjoy doing the exams every year, keeps me on my toes - I don't really like lecturing a subject I haven't sat the exam for in recent memory ;D
Post by: Atargod123 on October 23, 2017, 11:01:40 pm
Post by: liya1234 on October 23, 2017, 11:03:09 pm
Post by: .Woke. on October 23, 2017, 11:05:21 pm
Post by: avalansh7 on October 23, 2017, 11:08:00 pm
I thought it was actually a well-designed paper. I was looking at Q16 c for like 10 minutes, completely blank and then tried similar triangles and it worked out. Some of the questions made you work hard for the marks and it felt so good working them out
Can't disagree with that.
Post by: jamonwindeyer on October 23, 2017, 11:16:53 pm
For the t(2/3) question. Make t =m quadratic equation question. -27 to the power of 2/3 gives error on calculator why?
Just because of the order probably, but it is calculable - Try applying the power of two first (squaring) and then cube root it ;D
also just a question - for 16b) i did the first part equating the infinite sum to 2 and rearranged but got stuck there and did not relate it to the correct property where absolute value of r is less than one - would I still be able to get a mark for that?
Yep I reckon you would ;D
Hey guys, asking for a friend, what would a raw mark of 90+ be in this exam?
Raw 90ish would align to mid-high 90's I reckon ;D
Post by: Harry_Damon on October 23, 2017, 11:51:47 pm
Post by: jamonwindeyer on October 24, 2017, 12:23:04 am
What does everyone think the raw Mark cut off will be for a band four?
I reckon low to mid 60's as a super super super rough guess :)
Post by: Anfar3 on October 24, 2017, 12:23:10 am
Just wondering how accurate ur predictions for raw mark cutofffs for b6s are? How successful have u been in prev yrs? Just dont wanna get my hopes up too high lol.
Thanks
Post by: immagonow on October 24, 2017, 12:25:03 am
Post by: jamonwindeyer on October 24, 2017, 12:26:27 am
Hey Jamon,
Just wondering how accurate ur predictions for raw mark cutofffs for b6s are? How successful have u been in prev yrs? Just dont wanna get my hopes up too high lol.
Thanks
No idea, I don't track my success rate for these predictions, ahaha - But I think most people have found this exam tougher than those in recent years, you can use that idea and this database to come to your own conclusions :)
I got 89/100 for this exam and I was ranked 51/128 in my school, what band would I be sitting in?
Your exam mark will align to a B6, so it depends on the performance of your cohort! See this guide!
Post by: Abhi on October 24, 2017, 02:43:04 am
Post by: mariamoussa99 on October 24, 2017, 03:39:40 am
Post by: liya1234 on October 24, 2017, 06:33:15 am
Post by: Sahana2 on October 24, 2017, 07:34:40 am
for the kangaroo question, i got 870 because i used the unrounded answer of k . i gave the final answer in 2sf. do you think i will still get the mark? :(I DID THAT ASWELLL
Post by: Sahana2 on October 24, 2017, 07:46:07 am
Just wanted to know if I'm sitting at a 90 raw and a rank of 5/52. Am i eligible for a B6.
Post by: Annie657 on October 24, 2017, 08:32:03 am
So if I got 91 raw, is there any way my cohort would be able to bring me down from a b6? I just have a really bad rank (8/13) cause I got 77% in trials :/ they all found the exam hard so I am worried :/
Post by: avalansh7 on October 24, 2017, 08:36:10 am
So I've been doing some research and discussion with our teachers, and apparently a GP must have a common ratio that is a fixed value not equal to 0. So r cannot be zero. The only exception to this is the special GP, where a=0, r=0. i.e. 0,0,0,0,0. But if 'a' is any non-zero number to form a GP 2, 0, 0, 0, even though a limiting sum of 2 is reached, a GP doesn't exist, as Term2/Term1=0/2=0 but Term 3/2=0/0=undefined. So the answer should actually be 0<a<4, where a is not equal to 2. That probably explains why it is 3 marks. 1 for find Sinfinite --> 2=a/(1-r), therefore a=2(1-r). The other for graphing a vs r, or using another method to find the range of a (0<a<4), and the final for considering that the r=0 case doesn't make a GP. Sorry to everyone who got this q wrong (i did too), but its probably a q to set apart the really high mark students lobbying for state rank.
Post by: Thebarman on October 24, 2017, 09:05:56 am
How many booklets did everyone use in the end? I used 14
Post by: Zainbow on October 24, 2017, 09:40:46 am
That was a bloody tough exam. When it came to proving that sinA = sinB when L' = 0, I went about it in a different way than shown in the working on page one (i.e. I worked out sin A and Sin B separately and then more or less subbed it in), but I couldn't find the value of x from it. I immediately lost those 3 marks then :/ Overall, I'm not too confident on this one, but I knew that when going in. At least I've got a backup subject.
How many booklets did everyone use in the end? I used 14
Your concerns regarding the exam are similar to mine :( I think I used an entire booklet to try working out x in the sinA = sinB question, but I couldn't get it either. Now that I think about it, there were plenty of easier ways to answer the question lol but I can't go back now obviously.
As for booklets, I used up all the personalised ones plus 9 extras
Post by: jamonwindeyer on October 24, 2017, 10:18:26 am
Just wondering how scaling works, say i get an 83 rawmark, is that aligned to high 80s and then scaled once again?
Yep, so it is aligned to a Band cut off then scaled by UAC, here is the guide for anyone interested :)
honestly I felt like it was easier than many of the past years' exams. I think you only found it hard because you went the very long, hard way in some questions. in question 15 a ii you could have just found sina and sinb as trigonometric ration since the triangles were right angled. in question 16 c i you could have used the parallel intercept theorem.
I think I also made my life tough doing the exam in less than half the prescribed time ;) I totally agree that my approaches in Q16 could have been more efficient, but I personally still found the exam quite difficult in comparison to say, 2014 (my years exam). I think it was tougher than last years, on the whole, as well.
Important to know this is my perspective - Like, what I would consider 'difficult' is different to what you would consider difficult. But in talking to people broadly, I feel like people found this tougher than last years, I might even go find the 2016 Exam Discussion thread and compare a little later ;D
I mean, go you! If you've found the exam easy that bodes really well for your score - Good job ;D
Just curious about alignment - so if raw low 90's aligns to mid/high 90s, what would raw high 90s (97/98) align to?
Still high 90's, there isn't much room to move!! :)
HEY JAMON
Just wanted to know if I'm sitting at a 90 raw and a rank of 5/52. Am i eligible for a B6.
Yep, if your cohort performed well I reckon you are in with a good shot :)
That was a bloody tough exam. When it came to proving that sinA = sinB when L' = 0, I went about it in a different way than shown in the working on page one (i.e. I worked out sin A and Sin B separately and then more or less subbed it in), but I couldn't find the value of x from it. I immediately lost those 3 marks then :/ Overall, I'm not too confident on this one, but I knew that when going in. At least I've got a backup subject.
I reckon you'll get marks, because that would definitely have been the expected approach, rather than my brute force method ;D
Post by: avalansh7 on October 24, 2017, 10:24:38 am
Your concerns regarding the exam are similar to mine :( I think I used an entire booklet to try working out x in the sinA = sinB question, but I couldn't get it either. Now that I think about it, there were plenty of easier ways to answer the question lol but I can't go back now obviously.
As for booklets, I used up all the personalised ones plus 9 extras
For the sina=sinb, you should first differentiate to find dL/dx. From that you get an expression of dL/dx= (x)/root(x^2+25) -(9-x)/root(-(9-x)^2).
If you sub in dL/dx=0, x/root(x^2+25)=(9-x)/root((9-x)^+2+49) which if you look at the diagram is sina=sinb.
This is because the LHS and RHS of the above expression [x/root(x^2+25)=(9-x)/root((9-x)^2+49)] is sina=sinb in the triangles, using normal trig ratios and part (i).
Thus for the min distance travelled, when dL/dx=0, sina=sinb. (i.e. you don't need to find the actual value of x at this stage), but can use it to calculate x in (iii).
Post by: jamonwindeyer on October 24, 2017, 10:29:08 am
Hey Jamon,
So I've been doing some research and discussion with our teachers, and apparently a GP must have a common ratio that is a fixed value not equal to 0. So r cannot be zero. The only exception to this is the special GP, where a=0, r=0. i.e. 0,0,0,0,0. But if 'a' is any non-zero number to form a GP 2, 0, 0, 0, even though a limiting sum of 2 is reached, a GP doesn't exist, as Term2/Term1=0/2=0 but Term 3/2=0/0=undefined. So the answer should actually be 0<a<4, where a is not equal to 2. That probably explains why it is 3 marks. 1 for find Sinfinite --> 2=a/(1-r), therefore a=2(1-r). The other for graphing a vs r, or using another method to find the range of a (0<a<4), and the final for considering that the r=0 case doesn't make a GP. Sorry to everyone who got this q wrong (i did too), but its probably a q to set apart the really high mark students lobbying for state rank.
Hmm, very interesting! Thank you for the thoughts!
I definitely agree broadly, but I'm not 100% sure I agree in the context of the question. So while the way you've described a ratio poses issues for \(r=0\), realistically a common ratio of zero is okay (I can multiply by zero to get my next term, no problem), and it is within the \(-1<r<1\) range that NESA normally expects/mandates in this question type. We aren't taught \(|r|<1,r\neq0\), we are just taught \(|r|<1\).
So while enforcing \(r\neq0\) would probably be more mathematically correct, essentially, we are debating a semantic, and I don't know if NESA will even care about that semantic. High chance you get paid the full marks whether you considered it or not.
I wouldn't be surprised either way - I'm very torn, I guess we'll have to wait and see what they do! :)
Post by: Anything on October 24, 2017, 10:33:35 am
Hmm, very interesting! Thank you for the thoughts!Just adding on, conceptually wouldn't a limiting sum = 2 be approaching 2 when the number of terms approach infinite instead of being exactly equal to 2? (in the case of r = 0 and a = 2)
I definitely agree broadly, but I'm not 100% sure I agree in the context of the question. So while the way you've described a ratio poses issues for \(r=0\), realistically a common ratio of zero is okay (I can multiply by zero to get my next term, no problem), and it is within the \(-1<r<1\) range that NESA normally expects/mandates in this question type. We aren't taught \(|r|<1,r\neq0\), we are just taught \(|r|<1\).
So while enforcing \(r\neq0\) would probably be more mathematically correct, essentially, we are debating a semantic, and I don't know if NESA will even care about that semantic. High chance you get paid the full marks whether you considered it or not.
I wouldn't be surprised either way - I'm very torn, I guess we'll have to wait and see what they do! :)
Post by: jamonwindeyer on October 24, 2017, 10:39:23 am
Just adding on, conceptually wouldn't a limiting sum = 2 be approaching 2 when the number of terms approach infinite instead of being exactly equal to 2? (in the case of r = 0 and a = 2)
Hmm now that is a really good point - Okay, yeah, I'm strongly leaning that way mathematically now. I'm still skeptical whether NESA will mandate that you spot it - What I'll do is add it in red with a note that it might not be necessary for full marks, and I guess we'll keep fingers crossed! I hope they give it to the people who just put \(0<a<4\), would be nice to have more marks given out ;D
Post by: Anything on October 24, 2017, 10:42:18 am
Hmm now that is a really good point - Okay, yeah, I'm strongly leaning that way mathematically now. I'm still skeptical whether NESA will mandate that you spot it - What I'll do is add it in red with a note that it might not be necessary for full marks, and I guess we'll keep fingers crossed! I hope they give it to the people who just put \(0<a<4\), would be nice to have more marks given out ;DI didn't get it right in the exam, but i'm glad I could contribute to the discussion :)
Post by: adelaidecruz on October 24, 2017, 10:44:13 am
Post by: Anything on October 24, 2017, 10:47:36 am
Hi! Does anyone have any predictions on this year's B5 cutoff?
I believe Jamon mentioned mid to high 70's. Alternatively you can check out this link http://rawmarks.info/wiki/Mathematics. If you want to compare past years and make your own judgement.
Post by: jamonwindeyer on October 24, 2017, 10:54:31 am
I didn't get it right in the exam, but i'm glad I could contribute to the discussion :)
Really appreciate it! Fingers crossed you get the marks regardless ;D
I believe Jamon mentioned mid to high 70's. Alternatively you can check out this link http://rawmarks.info/wiki/Mathematics. If you want to compare past years and make your own judgement.
I think 2013 in that database would be a good recent reference ;D
Post by: Merin Thomas on October 24, 2017, 11:26:45 am
Thanks for the help (:
Post by: mfield on October 24, 2017, 11:28:01 am
Post by: jamonwindeyer on October 24, 2017, 11:30:10 am
Hey asking for a friend XD Wondering what the highest in 2013 was? And also, is it fine to do transversals ratio for question 16? :D
Thanks for the help (:
What do you mean by highest, like, highest mark? Probably still 100% but not sure!
And yep, transversals was fine and almost definitely faster than my method ;D
do you think a raw mark of 82 would be a band 6 for this paper. Personally found it difficult
Can't know for sure obviously but my thinking is that it would align to a 90 or above ;D
Post by: georgiia on October 24, 2017, 11:39:50 am
Hmm now that is a really good point - Okay, yeah, I'm strongly leaning that way mathematically now. I'm still skeptical whether NESA will mandate that you spot it - What I'll do is add it in red with a note that it might not be necessary for full marks, and I guess we'll keep fingers crossed! I hope they give it to the people who just put \(0<a<4\), would be nice to have more marks given out ;D
Thats sort of what i did. I showed that |r| < 1 and then said as r approaches -1 a approached 0 ect. but didn't write it like 0<r<4
Will I still get the marks?
(is subbed in -.9 and .9 to show this)
Also for the very last part of the last question, i messily proved that it bisected the angles but algebraically with pro numerals. Can that still get me the marks if i did it correctly? Thanks :)
Post by: Livchum on October 24, 2017, 11:40:16 am
Do you think between late 60s to mid 75 could potentially fall as a band 5?
Thanks.
Post by: jamonwindeyer on October 24, 2017, 11:43:59 am
Thats sort of what i did. I showed that |r| < 1 and then said as r approaches -1 a approached 0 ect. but didn't write it like 0<r<4
Will I still get the marks?
(is subbed in -.9 and .9 to show this)
Also for the very last part of the last question, i messily proved that it bisected the angles but algebraically with pro numerals. Can that still get me the marks if i did it correctly? Thanks :)
The substitution of values near 1 and -1 might not get you full marks but it isn't as rigorous, but you'll get 2/3 I'd say!
Yep, algebraic approach to that last question is fine provided it is correct :)
Hi Jamon!
Do you think between late 60s to mid 75 could potentially fall as a band 5?
Thanks.
I think that is definitely possible, probably low 70's but maybe lower, we'll have to see :)
Post by: georgiia on October 24, 2017, 11:47:56 am
The substitution of values near 1 and -1 might not get you full marks but it isn't as rigorous, but you'll get 2/3 I'd say!Thanks :)
Yep, algebraic approach to that last question is fine provided it is correct :)
Post by: engido244 on October 24, 2017, 11:56:49 am
Post by: Livchum on October 24, 2017, 12:04:29 pm
I think that is definitely possible, probably low 70's but maybe lower, we'll have to see :)
Thank you! So seeing as I have calculated my raw mark to be around the 70-71 mark, this could potentially be a band 5?
Post by: TheSpicyMeatBall on October 24, 2017, 12:10:24 pm
do you think both answers may end up being valid
Post by: TheSpicyMeatBall on October 24, 2017, 12:35:31 pm
Post by: Joeystrippa on October 24, 2017, 12:41:04 pm
I just let dL/Dx=0 and then moved the negative part of the equation over so it was x/square root (x^2+25) = 9-x/square root (49+(9-x)^2) and then from the triangles if you just found Sin(alpha) and Sin(beta) they were equal to the left and right hand respectively using Sin= opposite/hypotenuse (using pythagorus from i for the hypotenuse) so that LHS=RHS and therefore sin(alpha)=sin(beta). Idk that what worked for me and was much less work.
Post by: OliverN on October 24, 2017, 02:44:24 pm
The question about the three isosceles triangles (15A) the common answer is 36deg but did anyone else also get 108deg as an answer for obtuse-angled triangles? I am fairly sure there are two answers but curious what the general consensus on this is and if NESA is likely to recognise both answers.
I don't think that could be possible since you need to fit three of the angles, plus an extra, into 180 degrees for them to be parallel right? Could you perhaps elaborate further? :)If you visualise the triangles you have to line up the base side (lets call that AB) to be 180deg from the first side right, you probably think of it where you rotate the base side down making x smaller than what they present in the diagram but if you rotate it up and around making x bigger, the two sides will eventually become parallel as well the side will me upside down (so it will read as BA) but it's still parallel I would have thought. I will try to add some images to help visualise but I am not sure how this works.
Post by: jamonwindeyer on October 24, 2017, 02:46:35 pm
I'm looking at a raw mark of between 85-89 depending on how hard I'm marked and I'm 2/14 in the cohort. But 1st and 2nd are quite close and then there's a huge drop off. Do you guys think I could still slide/align into a band 6?
I reckon you are a good chance ;D
in question 14 ciii you reckon you should have used the rounded of value for k as that gives you a value of 880 years while using the complete value of k gives you 870 years
do you think both answers may end up being valid
I think both will be marked correct (poor question design to have that actually make a difference tbh) -> It is common practice to use the rounded value when it is given to you, but obviously using exact is also correct, so I think they'll pay both ;D
Post by: jamonwindeyer on October 24, 2017, 02:54:59 pm
I'm not sure if it has been posted here yet but I think there is a different way to do 16a) ii about Sin(alpha)=Sin(Beta).
I just let dL/Dx=0 and then moved the negative part of the equation over so it was x/square root (x^2+25) = 9-x/square root (49+(9-x)^2) and then from the triangles if you just found Sin(alpha) and Sin(beta) they were equal to the left and right hand respectively using Sin= opposite/hypotenuse (using pythagorus from i for the hypotenuse) so that LHS=RHS and therefore sin(alpha)=sin(beta). Idk that what worked for me and was much less work.
Yep, definitely a way better approach than my rushed brute force method and definitely correct (what they would have been anticipating people to do) ;D
I suppose on the plus side, I had almost zero work to do for (iii) and (iv), but I definitely still shot myself in the foot ;)
If you visualise the triangles you have to line up the base side (lets call that AB) to be 180deg from the first side right, you probably think of it where you rotate the base side down making x smaller than what they present in the diagram but if you rotate it up and around making x bigger, the two sides will eventually become parallel as well the side will me upside down (so it will read as BA) but it's still parallel I would have thought. I will try to add some images to help visualise but I am not sure how this works.
I see your images! Interesting perspective - I mean I personally think it warps the way the problem was presented a tad too much (although not to scale, the diagrams are still indicators of the arrangement of the problem), but it is definitely technically correct. I'd be interested to see if they gave the marks to someone who just did this! If you did both, well then you've got full marks anyway ;D
PS - What did you use for those images? Look slick af 8)
Post by: Shoesta on October 24, 2017, 03:32:54 pm
Post by: jamonwindeyer on October 24, 2017, 03:54:55 pm
What do you think the band 6 cut-off will be for this paper? :)
I think it will be mid to high 70's ;D
Post by: Stefan Kolar on October 24, 2017, 04:41:49 pm
Post by: jamonwindeyer on October 24, 2017, 04:42:55 pm
can somebody please send me a link to the paper.
NESA will upload it, based on how they've been going, tomorrow ;D
Post by: Stefan Kolar on October 24, 2017, 04:48:21 pm
Post by: ~BK~ on October 24, 2017, 04:48:57 pm
NESA will upload it, based on how they've been going, tomorrow ;D
well, nesa just put on the modern history one so i'd say jamon, your prediction would be right
just soo glad to have that paper behind me, i've been trying not to worry too much about what my mark will be ???
annnd, happy 21st jamon?
Post by: ~BK~ on October 24, 2017, 04:50:14 pm
ok, i want to see the questions, i actually think i did pretty well. Anyway do you have any tips for the upcoming physics exam? What things should i focus on?good on ya stefan?!?
that sorta q prolly best put on this thread: https://atarnotes.com/forum/index.php?topic=164552.0
Post by: jamonwindeyer on October 24, 2017, 04:56:31 pm
ok, i want to see the questions, i actually think i did pretty well. Anyway do you have any tips for the upcoming physics exam? What things should i focus on?
This guide might help! :)
annnd, happy 21st jamon?
Thanks heaps! ;D
Post by: avalansh7 on October 24, 2017, 05:03:11 pm
I'm not sure if it has been posted here yet but I think there is a different way to do 16a) ii about Sin(alpha)=Sin(Beta).
I just let dL/Dx=0 and then moved the negative part of the equation over so it was x/square root (x^2+25) = 9-x/square root (49+(9-x)^2) and then from the triangles if you just found Sin(alpha) and Sin(beta) they were equal to the left and right hand respectively using Sin= opposite/hypotenuse (using pythagorus from i for the hypotenuse) so that LHS=RHS and therefore sin(alpha)=sin(beta). Idk that what worked for me and was much less work.
Yeah i did that too.
Post by: kevvdev on October 24, 2017, 05:33:57 pm
Thanks! :D
Post by: jamonwindeyer on October 24, 2017, 05:47:14 pm
Hey jamon, for question 16a) ii, instead of proving sin(alpha)=sin(beta), i proved tan(a)=tan(b), does that work as well?
Thanks! :D
I think for full marks you would need to hit the line, \(\therefore \sin{\alpha}=\sin{\beta}\), but you could get partial marks!
I am looking at around 85 raw for the exam and I finished 13/52, but the difference between me and 1st is quite a bit. I averaged 77% in internals and got 81% in trials. Do you think I can get a band 6 still?
Definitely possible! ;D
Post by: aadharmg on October 24, 2017, 06:57:18 pm
There was this arithmetic and geometric sequences q that I couldn’t get for ages, had to cross out my working out multiple times >:( got it in the ens though :3 also the geometry proofs... :(Which question was the geometric sequences one?
Post by: Natasha.97 on October 24, 2017, 07:21:49 pm
Which question was the geometric sequences one?
I meant the limiting sum(16b) :P Arithmetic one was alright
Post by: goodguy on October 24, 2017, 08:12:24 pm
For the loan repayments question if i have correctly summed up the geometric series however forgot to change the months to years, so just did it as n=4, and instead got an answer of $23000, do you think i would get 0,1, or 2/3. Also, if my x value was wrong for 16aiii, but i proved that it was a minimum through testing points on either side of the incorrect f'x equation, would i receive the mark for carry through error?
thanks
Post by: NTK30 on October 24, 2017, 08:12:58 pm
Thanks so much for the solution. I hope you didn't get anything wrong because I had the same answers for most of paper. Just a few doubts below.
I remembered that question 11h only asked for the domain. If it's not a problem, can you tell me where you got the paper from? I want to confirm whether the range was asked or not.
For question 14c part iii, I had 870 (to 2 sigfig) using exact value (ln0.5)/5730). There is a 10 years difference with your answer (I think you used -0.00012). Which answer is right? Or will both be accepted?
Finally for question 16a:
- Part ii I believe you're supposed to write equations for sin(alpha) and sin(beta), then substitute them in to dL/dx.
- Part iii, I stated that alpha and beta must be acute angles. Therefore if sin(alpha) = sin(beta) then alpha = beta and thus tan(alpha) = tan(beta). I solved for x from here which was much easier. I know you said below that partial marks might be awarded if I simply solved with the tan equation. Will I get the full mark with this explanation?
- Part iv instead of doing a table of x and dL/dx, I just did a table of x and L. I showed that the x values on either side of x = 15/4 ( e.g. 3.65 and 3.85) gave larger values for L than at the stationary point. Is this sufficient for the proof?
Sorry for the long post and looking forward to your response. Thanks again.
Post by: jamonwindeyer on October 24, 2017, 11:20:08 pm
Hi,
For the loan repayments question if i have correctly summed up the geometric series however forgot to change the months to years, so just did it as n=4, and instead got an answer of $23000, do you think i would get 0,1, or 2/3. Also, if my x value was wrong for 16aiii, but i proved that it was a minimum through testing points on either side of the incorrect f'x equation, would i receive the mark for carry through error?
thanks
If you just forgot to convert from months to years that should just be one mark gone, as long as your approach was otherwise correct! And I think you would get marks for that COE ;D
Hey Jamon,
Thanks so much for the solution. I hope you didn't get anything wrong because I had the same answers for most of paper. Just a few doubts below.
You are welcome! ;D
Quote
I remembered that question 11h only asked for the domain. If it's not a problem, can you tell me where you got the paper from? I want to confirm whether the range was asked or not.
Range wasn't asked, only domain - I was rushing and added work for myself ;)
Quote
For question 14c part iii, I had 870 (to 2 sigfig) using exact value (ln0.5)/5730). There is a 10 years difference with your answer (I think you used -0.00012). Which answer is right? Or will both be accepted?
I've used the rounded, you've used the exact - I'm sure both will be paid ;D
Quote
Finally for question 16a:
- Part ii I believe you're supposed to write equations for sin(alpha) and sin(beta), then substitute them in to dL/dx.
- Part iii, I stated that alpha and beta must be acute angles. Therefore if sin(alpha) = sin(beta) then alpha = beta and thus tan(alpha) = tan(beta). I solved for x from here which was much easier. I know you said below that partial marks might be awarded if I simply solved with the tan equation. Will I get the full mark with this explanation?
- Part iv instead of doing a table of x and dL/dx, I just did a table of x and L. I showed that the x values on either side of x = 15/4 ( e.g. 3.65 and 3.85) gave larger values for L than at the stationary point. Is this sufficient for the proof?
Sorry for the long post and looking forward to your response. Thanks again.
So Part (ii), yep that was definitely the intended approach - Again, me rushing I added work for myself ;) (anyone who did what I did would absolutely get full marks as well). Part (iii), absolutely fine, provided you stepped through your logic as you have there!
Part (iv) is a little trickier, you would typically prove a minimum by table with the derivative. But, if you know the value of \(L\) then I see no reason that this proof wouldn't hold. So, I think you are okay there as well! :D
Post by: blokefromthesky on October 24, 2017, 11:53:19 pm
Post by: jamonwindeyer on October 25, 2017, 01:27:42 am
for the second part of the money question, I didnt create my own series (like using the sum formula to make the series). I just used the format of the series like it was in the question but up to four not two to answer the question. would i lose a mark for not creating a series but getting the right answer?
It was compounded monthly so you would have needed 48 terms, which is next to impossible to do without using the sum formula. You might lose a mark or two :)
Post by: Anfar3 on October 25, 2017, 02:40:22 am
For that same q^, I didn't get the answer coz i didn't do 2 sums i jst did the normal sum from the first part so got the wrong answer.
However, i created a series, used 48 terms, let A48= 80 000, did the algebra and calculations.
Only thing my sum missed the additional extra sum of the X deposit.
I kinda think ill only get 1/3 for that but any chance 2/3?
Thanks
Post by: PrimalPancake92 on October 25, 2017, 09:21:28 am
It was just the last question, everything else was pretty okay, I don't think I did many mistakes, but geometry proofs are my weakness, and part of 16 was geometry :( I think I got 3/15 for 16, which REALLY bothers me :/ )Dude why leave out 16?
Post by: jamonwindeyer on October 25, 2017, 10:20:05 am
Hey Jamon,
For that same q^, I didn't get the answer coz i didn't do 2 sums i jst did the normal sum from the first part so got the wrong answer.
However, i created a series, used 48 terms, let A48= 80 000, did the algebra and calculations.
Only thing my sum missed the additional extra sum of the X deposit.
I kinda think ill only get 1/3 for that but any chance 2/3?
Thanks
I think it would depend how you framed the first part of that two part question, but I think you will probably only get 1 mark unfortunately - It's a misinterpretation of the question rather than just forgetting something, at least in their eyes, but fingers crossed you get lucky! :)
Post by: Stefan Kolar on October 25, 2017, 12:44:03 pm
Post by: jamonwindeyer on October 25, 2017, 01:03:39 pm
Hey just to let u guys know, nesa released the paper
I've added a link to the OP ;D
Post by: Stefan Kolar on October 25, 2017, 01:20:45 pm
Post by: Anfar3 on October 25, 2017, 01:24:32 pm
Anyways if around 77-80 is raw b6 then what will an 86-88 raw get?
Post by: jamonwindeyer on October 25, 2017, 01:27:33 pm
hey Jamon just wanted to ask, for q16a ii) in the test i differentiated the length formula in the above part to get dl/dx, then i was stuck and i couldnt find x when dl/dx = 0 so i left it until i finished the rest of the paper. When i came back i had about 15-20min remaining and couldnt for the life of me find x, and so i just guessed random numbers and i actually got the answer. SO without any working out after the differentiation i just wrote x = 3.75 (15/4). then i subbed it into sinalpha and sinbeta and showed that they are equal. How many marks do u think i'd get for that question.
You'll likely lose a mark :)
Alright understandable Jamon, hope I get lucky hahaha!
Anyways if around 77-80 is raw b6 then what will an 86-88 raw get?
Perhaps mid 90's (<95)?? Really hard to say because the alignment algorithms aren't linear, so I'm unsure when it isn't near a Band cut-off ;D
Post by: Merin Thomas on October 25, 2017, 07:51:42 pm
Post by: jamonwindeyer on October 25, 2017, 09:29:50 pm
Hey am I the only HSC student that dont know how this system works :( *left out at the corner of the room* anyways, when people say b6 cutoff is eg. 85, does that mean a raw mark of 85? so like... u need to get 85 or above raw to get b6? plus its usually said that above 90% is considered b6. And the bio exam was okayish~ and people expect 93 to be b6 cutoff o.o *jaw drop; pen drop; gasp & clap* so does gettin 91 (above 90) get b6 or should it be above 93 o.o sanks
Hey! The full guide on the process is here, but you've essentially got it! A Band 6 cutoff of 85 means that anyone with a raw mark of 85 or above will get a B6 equivalent mark as their HSC Exam mark :)
Post by: Merin Thomas on October 25, 2017, 10:40:14 pm
Post by: alihkhan8 on October 25, 2017, 10:55:56 pm
Post by: Krncy on October 26, 2017, 01:03:47 am
Post by: JC13 on October 26, 2017, 01:16:55 am
100% that im getting a band 2-3
Post by: Krncy on October 26, 2017, 01:27:53 am
Post by: PrimalPancake92 on October 26, 2017, 02:36:51 pm
Post by: PrimalPancake92 on October 26, 2017, 02:45:09 pm
Alright understandable Jamon, hope I get lucky hahaha!Then what is the band 6 cutoff for this year?
Anyways if around 77-80 is raw b6 then what will an 86-88 raw get?
Post by: jonathanzhou22 on October 26, 2017, 02:55:19 pm
I believe for the financial question the final dollar value should be rounded up, not down as otherwise the goal cannot be met. I put down $4020 in my exam, what do you think?
The solution for 16 a) could be made simpler by observing that sin(a) = x / (x^2+25)^2 and sin(b) = (9-x) / (49-(9-x)^2)^2, which means when the derivative equals zero, sin(a) = sin(b).
Post by: alihkhan8 on October 26, 2017, 05:58:51 pm
thankuuu (: Also, is it true that getting b6 in all units guarantee 90+ atar? (my sub:math, math ext 1, phy, chem, bio, eng stand)A band 6 in even 2 of your subjects and rest mid-high band 5 will get you a 90 atar easily
Post by: blokefromthesky on October 26, 2017, 10:32:33 pm
Post by: Wowser1212 on November 05, 2017, 02:42:21 am