No problem. Do you want to tag me on that FP2 thingy you were asking me about earlier so I can have a look at it (not right now because I'm not home) but when I'm back? :smile:

Reply 87

economicss

Original post by Zacken

No problem. Do you want to tag me on that FP2 thingy you were asking me about earlier so I can have a look at it (not right now because I'm not home) but when I'm back? :smile:

Yeah that would be great, thank you :smile:

Reply 88

Zacken

Original post by economicss

Yeah that would be great, thank you :smile:

Thanks!

Reply 89

economicss

Hi please could someone explain question 2b of the june 2014 paper, why is it we divide by 2 squared for the variance rather than 2? Thanks :-)

Reply 90

Kevin De Bruyne

Original post by economicss

Hi please could someone explain question 2b of the june 2014 paper, why is it we divide by 2 squared for the variance rather than 2? Thanks :-)

Please link the paper or a picture of the question :h:

Reply 91

Zacken

Original post by economicss

Hi please could someone explain question 2b of the june 2014 paper, why is it we divide by 2 squared for the variance rather than 2? Thanks :-)

I haven't seen the question because I'm saving that paper as a mock but are you aware (from S1 and S3) that

\text{Var}(aX) = a^2\text{Var}(X)

and

E(ax) = aE(X)

so that

\text{Var}(\frac{X}{2}) = \left(\frac{1}{2}\right)^2\text{Var}(X) = \frac{1}{4}\text{Var}(X)

Reply 92

Ayman!

Original post by economicss

Hi please could someone explain question 2b of the june 2014 paper, why is it we divide by 2 squared for the variance rather than 2? Thanks :-)

I've actually done this question on a mock - you should follow techniques learnt in S1 that Zacken mentioned and it's simple from there.

Spoiler

Reply 93

economicss

Original post by aymanzayedmannan

I've actually done this question on a mock - you should follow techniques learnt in S1 that Zacken mentioned and it's simple from there.

Spoiler

Thanks so much, should have taken the 1/2 outside of it! Please could you explain how question 6c on this paper https://869d950bf149eefd5cd2652b400160ceb38ca5c7.googledrive.com/host/0B1ZiqBksUHNYVGVDMmVJYzVnRnc/June%202014%20QP%20-%20S3%20Edexcel.pdf is done using confidence intervals, as I understand the normal distribution method but not too sure how it can be solved using confidence intervals? Thanks :smile:

Reply 94

economicss

Hi, does anyone know please whether we could be asked to do a test like that one in question 4i here? From an OCR paper :smile:

https://f1f559d498e385d34687bce0088efc8d3456c121.googledrive.com/host/0B1ZiqBksUHNYc2FITWYzdkFrZ1U/Specimen%20QP%20-%20S3%20OCR.pdf

Reply 95

Ayman!

Original post by economicss

Hi, does anyone know please whether we could be asked to do a test like that one in question 4i here? From an OCR paper :smile:

https://f1f559d498e385d34687bce0088efc8d3456c121.googledrive.com/host/0B1ZiqBksUHNYc2FITWYzdkFrZ1U/Specimen%20QP%20-%20S3%20OCR.pdf

I think this is out of spec. I'm not certain though.

Reply 96

Zacken

Original post by economicss

Hi, does anyone know please whether we could be asked to do a test like that one in question 4i here? From an OCR paper :smile:

Nope, the only continuous distribution we work with is the normal and uniform, not random PDF's like those. You could, however be given a continuous uniform PDF and asked to find the expected frequency though, it's not really that different.

Reply 97

economicss