Edexcel S3 - Wednesday 25th May AM 2016

Posted from TSR Mobile

I rounded both up. Do you reckon we'll lose a mark for that? I doubt it

My answers - I thought t was fairly standard

1a) More representative, individual strata estimates availiable
1b) random process, no interviewer bias

2) 5.61 and I think you rejected

3a) When the data isn't bivariate noral
b) 0.75 and I think you rejected
You accepted the pmcc question
e) You HAD TO say about ranks - days where sales of ice cream ranked highly, ranked highly for sunglasses

4a) 0.7794
b) 760,302.25
c) 0.0107

5a) 1.95 and you rejected
b) Var of sample = var of population. Samples are independent of each other. CANT MENTION CLT - as its not an assumption, it's a thorem
c) tricky - 12.7

6a) Test statistic was 4.1 and you accepted
b) r= 26.78 s= 16.07
c) Test statistic was 14.65 you reject

7a) 19.15%,19.85%
b) Paul shoud tell them to lover stated weight
c) n=44

Who agrees?

did the paragraph in q6 say p=0.3 was estimated? or did they say she believes p=0.3 in the binomial goodness of fit.

"believes that the data can be modelled by Binomial distribution with p = 0.3" i think which means the "believes" part refers to the Binomial part of the question and 0.3 wasn't estimated.

good!, gues i havent lost more stupid marks!

Large populations is for systematic though. I'm annoyed I didn't write for large samples but donno about large population dude

Fair to say:
A- 65/66
A*- 70/71

Given it was slightly harder than fp2 June 2015 I'd guess similarish but also less people do stats 3 than fp2 so might be the same.

What exactly are you talking about? The estimator for sample mean or sample variance?

i don't see why you compare it to a fp2 paper when this is an s3 paper. comparing to last year's s3 paper which was much harder, i think the gb's will be A*>72, A>66 p.s. last year's fp2 paper was considered to be quite easy i think

This is clearly inaccurate: A* boundaries for past few years:
70
69
68
68
69 (71)
66

It has never been >70 except on an R paper.
This paper also had several tricks (CLT not at assumption, lose 2 DoF for a chi squared test) and because there were 3 chi squared was on the time pressured side => less time to check => more silly mistakes). Predict A* boundary 68 -69. No way is it 71 let alone higher.

This is clearly inaccurate: A* boundaries for past few years:
70
69
68
68
69 (71)
66

It has never been >70 except on an R paper.
This paper also had several tricks (CLT not at assumption, lose 2 DoF for a chi squared test) and because there were 3 chi squared was on the time pressured side => less time to check => more silly mistakes). Predict A* boundary 68 -69. No way is it 71 let alone higher.