Edexcel S3 - Wednesday 25th May AM 2016

Can I ask which paper is that one? Thanks!

let me know as well (Y)

13R.

is a discrete uniform basically a pdf?

For goodness of fit tests, say you have a binomial distribution, do you work out the parameter p by default? Or do you just assume it. E.g. in an event with two outcomes, do you assume p is 0.5, or calculate it from observed data? I calculated in one q and lost some marks as it was supposed to be assumed.

Ohhh, of course, sorry, there is another key difference - I see what you were asking now.

a) asks for the distribution of the orchids themselves, not the distribution of the mean of them.

So you use that a population is distributed ~N(20.1,0.5^2) for a) and a mean of n samples is distributed ~N(20.1, 0.5^2/n) for b).

@Zacken

Does anyone have a link for the S3 June 2015 exam ?
Thanks in advance.

ye i thought it was something to do with question a not mentioning the mean, is it basically n=1 for the orchids (not the mean)?

Way to go Edexcel, loving the consistency.



Edexcel website.

(seriously the 10th time I'm having to say this...)

I suppose you can think of it as taking a sample of 1 (hence n=1) so yes




Apologies - I will put it in a massive font in the OP.

Apologies - I will put it in a massive font in the OP.

Love it. I expect now I'll be saying "See OP."

A lot shorter, I suppose

Thanks for the effort - it can be frustrating.

burning question guys:

ex3D q8a, why dont you use continuity correction - arent you going from poisson to normal?!?

No, you are using the CLT which states that the sample mean is normally distributed without continuity corrects no matter what the underling population distribution is.

okay agreed! but then the red box on p37 - what and when is that relevant?

AND also looking at it now, why do you even need to use CLT for that question for part a? cant you just scale up poission mean and work out probability s2 style?

I agree.

Right back at you! You seem to deal with it much better though. How'd your uni exams go?

It's not relevant.

No, just because the population is distribution poisson doesn't mean the sample mean is as well.