VCE Methods Question Thread!

[plsbegentle]

To be safe, is it better to use un-rounded figures for things such as probability or standard deviation in the following questions, even when in a previous question you have to work out a rounded figure? Thanks!!

I would say so, I've seen many examiner reports use the unrounded figure instead of the rounded especially for conditional probability. Or you can just use the formula again from the previous question, if you really want to be safe.

[passbleh]

Hey guys,

I came across a confusing question in the cambridge textbook. Chapter 17 review question 3 tech free and am a bit confused. I have attached the question and answers. I understand 3a which is just simple substation but for the rest i just don't understand where to begin. So if someone has already done this or is willing to help that would be appreciated.

Thank you

[Eric11267]

Hey guys,

I came across a confusing question in the cambridge textbook. Chapter 17 review question 3 tech free and am a bit confused. I have attached the question and answers. I understand 3a which is just simple substation but for the rest i just don't understand where to begin. So if someone has already done this or is willing to help that would be appreciated.

Thank you

b)i) a 95% confidence interval means there is a 95% chance the actual proportion will be within the interval. So its just a binomial distribution with chance of success at 0.95 and number of trials at 5
ii) see above
iii)see above
iv) this is expected value of a binomial distribution
c) pooling the results is adding the total number of successes together. So the proportion would be 311/500 and then everything else is the standard

[passbleh]

b)i) a 95% confidence interval means there is a 95% chance the actual proportion will be within the interval. So its just a binomial distribution with chance of success at 0.95 and number of trials at 5
ii) see above
iii)see above
iv) this is expected value of a binomial distribution
c) pooling the results is adding the total number of successes together. So the proportion would be 311/500 and then everything else is the standard

Legend!
that was soo simple, thank you soo much for your help!

[Yueni]

Hi,

For the NHE E1 https://imgur.com/a/QRDC8

How do we also get c>2 as a solution too?

A way to look at this question, though not intuitive in the slightest may be to consider the graph

Here we have the solutions to our inverse function, which you have clearly understood.

Looking at the graphs we know that c moves g(x) left and right. We know that moving it left will generate solutions if we start at c=0. We also know that the largest (or smallest, depending on the case) value of c in which there will be two solutions is the c value when Solving for this we get and Thus we have and You must also consider that there is most certainly more than one value in which the inverses only intercept once, and this should be a trigger to consider some creative options.

EDIT:

Upon further inspection, I think I may be able to offer a more intuitive solutions:

Consider the function It has a stationary point at As our square root function is positive we will take the positive band of this quadratic. Thus our domain for our inverse will be Rearranging the function g we can obtain the following From this we can state that From here, there will be one solution when these two x values are the same or when they intersect in the allowable domain. That is And Solving for this we get and

[mano91]

Just a couple of questions:
How does sqrt (c-1) = -sqrt(c-1) produce any solutions?
and why does sqrt (c-1)>1?

Thank you

[snowisawesome]

How much ability difference is there between a raw 29 study score student and a raw 42 study score student in methods?

[QueenSmarty]

This is probably the dumbest question I've asked, but how do you work out q10 from 2009 exam 2 (multiple choice)?

[Yueni]

Just a couple of questions:
How does sqrt (c-1) = -sqrt(c-1) produce any solutions?
and why does sqrt (c-1)>1?

Thank you

Consider the following The quantities will equal when for any real value of a. This occurs when Thus we can solve for Which produces . Obtaining Requires you to consider the fact that at any point an inverse intersects within the allowable domain it will have strictly one solution. The allowable domain is

[Yueni]

This is probably the dumbest question I've asked, but how do you work out q10 from 2009 exam 2 (multiple choice)?

You add the probabilities left to right until you reach a value equal to or greater than 0.5. The respective x value for that probability is your median.

[plsbegentle]

This is probably the dumbest question I've asked, but how do you work out q10 from 2009 exam 2 (multiple choice)?

So, you basically have to find the probability that exceeds 0.5. So if you start from left to right, 0.4+0.2=0.6,so 1 is the median. This also works if u work it backwards, so from right to left. 0.1+0.3+0.2, which makes 1 the median as well.

Hope that makes sense

EDIT; Yueni beat me too it

[QueenSmarty]

Thanks Yueni and plsbegentle!

Is question 3 from 2010 exam 2 still part of the study design?

[plsbegentle]

Thanks Yueni and plsbegentle!

Is question 3 from 2010 exam 2 still part of the study design?

No, if you see anything with | |, its not in the study design, but still a fairly simple question, if you want, just replace the absolute function with round brackets.

[Rieko Ioane]

Hi,

For this Q https://imgur.com/a/ffr3c

How is the answer getting tantheta = 1/2?

This is the very last Q of VCAA 2011 E1 if you need more context.

Thanks

[Eric11267]

Hi,

For this Q https://imgur.com/a/ffr3c

How is the answer getting tantheta = 1/2?

This is the very last Q of VCAA 2011 E1 if you need more context.

Thanks

The previous part of the question asks you to show that a turning point occurs when BD=2CD. And since tan is just a ratio of two sides, tan(theta)=CD/BD=1/2