VCE Methods Question Thread!

[xxxjss]

could someone please help me with question 8c of the 2019 NHT methods exam 1?

i don't understand how you use information from previous questions to obtain the answer (nor do i know how to obtain the answer lol)

many thanks!!

edit: sorry the screenshot is pretty much useless if you don't have the question lol. i was going to link the pdf to the exam but i'm not sure if that's allowed

my class followed that Pr(W=k) must be greater than Pr(W=k+1) by using the logic that as in terms of binomial Pr(X=1) has a higher prob than Pr(X=2) etc
thus 5(k+1) > 50 - k
solve for k and get 15/2 which is 7.5 and must check whether k=8 or k=7 (since discrete) satisfies Pr(W=k) > Pr(W=k+1); would find k=8 satisfies whilst k=7 does not

[disone]

could someone please help me with question 8c of the 2019 NHT methods exam 1?

i don't understand how you use information from previous questions to obtain the answer (nor do i know how to obtain the answer lol)

many thanks!!

edit: sorry the screenshot is pretty much useless if you don't have the question lol. i was going to link the pdf to the exam but i'm not sure if that's allowed

how to you even do the whole question ... it dont make much sense

[interessant]

Just to confirm, is it 100% ok to write with pencil on both the exams?

Apparently they'll still mark it but it'll just be difficult for them.

[Massimooo123]

my class followed that Pr(W=k) must be greater than Pr(W=k+1) by using the logic that as in terms of binomial Pr(X=1) has a higher prob than Pr(X=2) etc
thus 5(k+1) > 50 - k
solve for k and get 15/2 which is 7.5 and must check whether k=8 or k=7 (since discrete) satisfies Pr(W=k) > Pr(W=k+1); would find k=8 satisfies whilst k=7 does not

Starting by solving 5(k+1)>50-k and testing for 7 and 8 is more valid than evaluating 50/6 = 8.333 and testing for 8 and 9. If you take X~Bi(5,0.598), for example, 5*0.598 gives you an expected value of 2.99. But, as it turns out, Pr(X=4)>Pr(X=2). So, while the 50/6 method would indicate you to test for 2 and 3 as 2<E(x)<3, you would ACTUALLY need to test for 3 and 4, if you had derived an equation for Pr(X=k+1)/Pr(X=k) with those values. For this specific question, Pr(W=9)>Pr(W=7), but you can't prove that merely by the fact that 50/6 is closer to 9.

Either way, you could technically start by just guessing that k is around 8. As long as you show that Pr(W=9)<Pr(W=8) AND Pr(W=7)<Pr(W=8), that's enough to show Pr(W=8) has the greatest value. So it doesn't really matter how you get there regardless.

[harold17]

Hi Guys
Is knowing the inverse of a 2x2 matrix knowledge needed for exam 1?
Cutting it thin here, I know, but would be helpful if someone could clarify.
Thanks

[Massimooo123]

Hi Guys
Is knowing the inverse of a 2x2 matrix knowledge needed for exam 1?
Cutting it thin here, I know, but would be helpful if someone could clarify.
Thanks

It's not on the study design, and they've never asked for an inverse matrix on the exam. I'm not an expert, but a lot of teachers would be very angry if it did come up, so I doubt it would. All you need to know for matrices is multiplication, addition and subtraction, and transformations.

[milanander]

All you need to know for matrices is multiplication, addition and subtraction, and transformations.

Transformations, yes definitely; but I thought multiplication/addition/subtraction are 1/2 knowledge? Pls correct me if I'm wrong.

[colline]

Transformations, yes definitely; but I thought multiplication/addition/subtraction are 1/2 knowledge? Pls correct me if I'm wrong.

'

According to the VCAA study design, you need to know "the matrix representation of points and transformations of the plane", so no multiplication, addition, and subtraction.

[S_R_K]

'

According to the VCAA study design, you need to know "the matrix representation of points and transformations of the plane", so no multiplication, addition, and subtraction.

Unless you just want to rote learn how a matrix equation represents dilations, reflections, and translations, then you should understand how to multiply and add matrices.

That said, it is extremely unlikely that you'll be asked to show any by-hand matrix calculations.

[milanander]

Thanks colline and S_R_K.
---

VCAA 2018 E2 Q4d(ii)
sorry for the dumb question but how do you explain WHY the confidence interval is different? I don't understand the examiner's report, it literally says because there's different numbers, but surely it's not that straightforward??

[colline]

VCAA 2018 E2 Q4d(ii)
sorry for the dumb question but how do you explain WHY the confidence interval is different? I don't understand the examiner's report, it literally says because there's different numbers, but surely it's not that straightforward??

It’s not because the numbers are different but rather because the number in question is not within the range of confidence interval given.

Btw, never apologise for asking questions

[milanander]

It’s not because the numbers are different but rather because the number in question is not within the range of confidence interval given.

Btw, never apologise for asking questions

Oh ok thanks so much.

Good luck for the exam tomorrow everyone

[disone]

does anyone know how to do the vcaa 2018 exam 2 question 5 part e-g

[darthnucleus]

2016 VCAA Meth 2
MC
9 - I have no ide how they got the answer and the examiners report isn’t making any sense
10 - don’t know what to do
11 - is it just trial and error?
19 - I got the combined equation 5b^2+4b but don’t know what to do after
20 - I don’t understand

ER
1d - how do you calculated f’=1?
1e - how does 2acos turn into -2asin?
1f - why is the tan not negative?
3d-h - I don’t know how to get the answer
4fi and ii - I don’t know what to do

[studyingg]

For the last part, would it have been acceptable to use limits? As in, limit of A(k) as k --> 1 from the negative/left direction is equal to 2 and the limit of A(k) as k --> 0 from the positive direction is equal to 0 ... If it is, do you have to actually evaluate the limit by hand or is it sufficient to say lim k --> +infinit --- is that calc syntax btw?