VCE General & Further Maths Question Thread!

[TheMereCat]

2004 exam 2

Oh, i see. So you just found the area of the triangle differently.

I can see why only 4% got it full marks. I can see many people making the same mistake I did at first glance.

[MightyBeh]

2004 exam 2

Oh, i see. So you just found the area of the triangle differently.

Yep! I actually really liked this question, I should give those older exams a shot 

[TheMereCat]

Yep! I actually really liked this question, I should give those older exams a shot 

Yeah this question was actually really cool. Geo  and trig is my favourite module so if there are more questions like these I should give those older exams a shot.

[coolbeans]

My teacher all year has been teaching us business maths, networks & decision maths and matrices. I got my sac back for business and I did terrible so my cousin has decided to last minute teach me trig/geometry for the exam IN ONE WEEK! Does anyone think this a reasonable/horrible idea, considering business was my weakest subject in further? I find trig and geometry a lot simpler and less complicated than business (because business has sooo many formulas to remember) but i'm just worried I'm going to crash and burn when the exam comes around!!

[Aaron]

My teacher all year has been teaching us business maths, networks & decision maths and matrices. I got my sac back for business and I did terrible so my cousin has decided to last minute teach me trig/geometry for the exam IN ONE WEEK! Does anyone think this a reasonable/horrible idea, considering business was my weakest subject in further? I find trig and geometry a lot simpler and less complicated than business (because business has sooo many formulas to remember) but i'm just worried I'm going to crash and burn when the exam comes around!!

It is a risk (no doubt), but if you think you can understand that topic more than business maths... I say go for it. I contemplated doing this when I was in Year 12, and I honestly regret not doing it. I was the opposite, I hated geo/trig.

Just make sure you go over the past exams and ensure that you understand how to solve problems in geo/trig, because you really need to solve them at a fast pace (so to speak), as 90 minutes isn't a significant amount of time. This is what stumps alot of people in Further, careless mistakes.

[mattcorr_]

Matrices module, 2011, Exam 1, Question 8

The assessors report does not cover this module because it was completed 'reasonably well' which leaves illiterates like me, helpless

Can someone show a worked solution, my cas does not want to solve for x with these types of questions

[MightyBeh]

Matrices module, 2011, Exam 1, Question 8

The assessors report does not cover this module because it was completed 'reasonably well' which leaves illiterates like me, helpless

Can someone show a worked solution, my cas does not want to solve for x with these types of questions

Key word is inverse.
According to the question, , or 'k' in matrix A is equal to the inverse in the same place.

To find the inverse manually, you need to work out the determinant (ad-bc). Working's attached if that doesn't clear it up for you

[n.a]

Matrices module, 2011, Exam 1, Question 8

The assessors report does not cover this module because it was completed 'reasonably well' which leaves illiterates like me, helpless

Can someone show a worked solution, my cas does not want to solve for x with these types of questions

So basically:

1: Using CAS, find the inverse of the matrix in the question.
2: This gives you a matrix with all inverse values in terms of k.
3: The one that we are concerned with is the one in the corresponding position to k in the original matrix; that is: (-9/4(4k-9)) -1/4.
4: W know that these two are equal because the question tells us that the matrix equals it's inverse.
5: So now, put these into the CAS and solve for k.
6: CAS will give you k=0 or k=2.
7: Try both of them in the matrix and find their inverses. Only k=2 will give you the exact same matrix as the inverse.
8: Therefore, answer is D.
Hope that helps!

[ineedbiohelp]

Hey Further Maths students,
Im having trouble with understanding this question and why they used the volume scale factor, since the radius for both shapes is the same, wouldn't the sides be out of proportions and therefore the use of k, k^2 or even k^3 become impossible?
-i have attached the question, but its the first time doing this so i may have done it wrong, so ill link the VCAA exam it is off.
http://www.vcaa.vic.edu.au/Documents/exams/mathematics/2009furmath2-w.pdf    Page 15, Q4B TRIG

-VCAA used the solution of: (20/50)^3=0.064, 1-0.064=93.6%        I just dont understand the first bit, and if anyone has a different way of solving this or explaining this, that would be great! I prefer longer methods, like actually finding the volume of both, although this did not work when i tried that....

Thanks in advance, good luck everyone.

[MightyBeh]

Hey Further Maths students,
Im having trouble with understanding this question and why they used the volume scale factor, since the radius for both shapes is the same, wouldn't the sides be out of proportions and therefore the use of k, k^2 or even k^3 become impossible?
-i have attached the question, but its the first time doing this so i may have done it wrong, so ill link the VCAA exam it is off. (Image removed from quote.)
http://www.vcaa.vic.edu.au/Documents/exams/mathematics/2009furmath2-w.pdf    Page 15, Q4B TRIG

-VCAA used the solution of: (20/50)^3=0.064, 1-0.064=93.6%        I just dont understand the first bit, and if anyone has a different way of solving this or explaining this, that would be great! I prefer longer methods, like actually finding the volume of both, although this did not work when i tried that....

Thanks in advance, good luck everyone.

Same method as shown by the VCAA, but with diagrams because why not. In the assessor's report, it looks like people assumed that the radius would stay the same even though there's less oil; which is pretty reasonable until you draw a diagram. Attached my poorly drawn working out if it makes it any clearer

[StupidProdigy]

Hey Further Maths students,
Im having trouble with understanding this question and why they used the volume scale factor, since the radius for both shapes is the same, wouldn't the sides be out of proportions and therefore the use of k, k^2 or even k^3 become impossible?
-i have attached the question, but its the first time doing this so i may have done it wrong, so ill link the VCAA exam it is off. (Image removed from quote.)
http://www.vcaa.vic.edu.au/Documents/exams/mathematics/2009furmath2-w.pdf    Page 15, Q4B TRIG

-VCAA used the solution of: (20/50)^3=0.064, 1-0.064=93.6%        I just dont understand the first bit, and if anyone has a different way of solving this or explaining this, that would be great! I prefer longer methods, like actually finding the volume of both, although this did not work when i tried that....

Thanks in advance, good luck everyone.

Alternative way (basically the same but with more working and a bit more intuitive)-Choose an arbitrary radius, say for example 2cm (initial radius when h=50). Then find the little radius at h=20 by scaling down using your arbitrary value. So 2/50=r/20 --->r=4/5. So Big volume=(pi*2^2*50)/3 and small volume=(pi*(4/5)^2*20)/3. Now just do 1-(small volume/big volume)

[ineedbiohelp]

Thank you so much!
Those diagrams will actually help me with future tricks that VCAA will use as i completely forgot the radius of a cone is not uniform (decreases as you reach the pointy end)
-I completely understand this now, once again thank you!

[ineedbiohelp]

Previous message was to the first response......

-This is to the second response i got.....
Oh that also makes sense, that shall be helpful if they use another type of shape to try and trick me in the exam, thank you!

[kavmeh]

Hi everyone
I was going over all the past exam papers I have done and I am stuck on question 13 from Core 2006 exam 1.
I'm just confused about how they got 0.86 in the formula on VCAA report

[Lawyer]

Hi everyone
I was going over all the past exam papers I have done and I am stuck on question 13 from Core 2006 exam 1.
I'm just confused about how they got 0.86 in the formula on VCAA report

deseasonalised number of unemployed = 373.3 – 3.38 × month number
The month number is June which is 6
Thus 373.3-3.38x6 = 353.02.

But the question asks for actual number (actual number= deseasonalised figure x seasonal index)
Thus 353.02x0.86.
The 0.86 is the seasonal index of June which is shown in the box below Question 11- that explicitly says it refers to questions 11,12 and 13.

Thus the answer is 303.5 which is closest to A.