Edexcel S3 - Wednesday 25th May AM 2016

Could the conditional probabilitlity/ percentage points/ other S1 stuff be asked in S3.

Could the conditional probabilitlity/ percentage points/ other S1 stuff be asked in S3.

Yes, although it'd likely to be different to normal conditional probability in that you have to interpret what the condition is, not just use a formula.

An example is in S2, June 2014 about mosquitos if I remember correctly.

And percentage points.. I don't see why they wouldn't

And make sure you can deal with modulus functions as well (e.g. P(mod(x) > 5) for some distribution).

Technically yes. Wouldn't really expect it though. Well, conditional probability would be more likely.

are there any jan 16 / jan 15 ial papers or anything?

also, do you guys reckon s3 will be harder / easier than last years paper?

are there any jan 16 / jan 15 ial papers or anything?

also, do you guys reckon s3 will be harder / easier than last years paper?

https://869d950bf149eefd5cd2652b400160ceb38ca5c7.googledrive.com/host/0B1ZiqBksUHNYVGVDMmVJYzVnRnc/June%202013%20(R)%20QP%20-%20S3%20Edexcel.pdf

For question 8b when it is a fraction, do you still square the variance?

Yeah

Is there a reason why please? If it was 1 instead of the fraction then no squaring - right?

part b is ridiculous that is d1 inequalities wtf

Yeah
edit: Well actually I'm not quite sure what you mean. When finding the variance of C - 4/5D you do Var(c) + (4/5)^2Var(D) if that's it

I don't get how you square, if it is not independent?

Well C and D are independent variables?

https://771a1ec81340d97ae9ed29694f73dd633b1c7c70.googledrive.com/host/0B1ZiqBksUHNYV1BTbDkxWXZCVmc/CH3.pdf


Can smoeone explain EXB Q6 b and c please, where does p come about and how to work out the final part.

Definition of bias of an estimator, eg the estimator xbar, is E(Xbar) - parameter that is being estimated.

In your textbook you'll probably have seen it as E(theta) - theta. So you are told in the question that you are trying to estimate p with the estimator xbar, so the bias is E(xbar) - p, and the unbiased estimator is the one required for E(f(xbar)) - p = 0 where f is some function of xbar (in this case, you divide it by 10 since E(xbar) = 10p, so E(xbar/10) = 1/10 E(xbar) = 10/10 p = p, and then p-p=0 so xbar/10 is unbiased.

So when would we test for H1: p<0 for spearmans rank (apart from a standard q where it is asking if there is disagreement)? Like testing someone's claim would it be likely that it is mostly p>0 or p not equal to 0?

Also could we be asked q's involving pdfs and cdfs from s2? Maybe even having to use clt on it?

If rankings are tied in spearmans rank say at 5 there are two values which are equal then would we give it a value of 5.5, I tried doing this for a question but the difference, d was not equal to 0.