OCR S2 22nd June 2010

Hey everyone, how did it go? I thought mine went very well, hoping for 90%+ from that, I was told I could keep my exam paper so if anyone is wanting it for reference for the following discussion I will be happy to upload it!

Didn't both copying down what I wrote for the why is it suitable.. type questions

My Answers (not THE answers):
1
i)
a) 0.133
b) 0.0580

2
i) 0.2616
ii) About how there is a chance that 2 of the same serial will be picked, but sample is large so chance is small, so there is a chance the answer is invalid.

3
i) 9.501
ii) 0.3449

4
1.91%>1% so accept H_0

5
i)
a) t > 32.6
b) 0.0645
ii) 21 months

6)
a) 0.0923
b)
i) np = 196 !< 5
ii) changing to P(X greater than or equal to 6) with Po(200*0.02): 0.2149

7
mean = 56.95
estimate of population variance = 2.864
6.41% > 5% so accept H_o

8
i) Show that
ii) 0.75
iii) 4.32

Can anyone confirm these answers? Quite eager to know how I did

On question 3 why has everyone used a continuity correction of 0.5 not 1/180 (1/2n)...am I being thick?

NO WAY WAS THE LAST PART 4.33??? I integrated between 1.5 and 1 instead of 2 and 1 which is what I'm guessing most of you did because the question said P(X<2)=0.9
I used continuity correction :|
Reckon I'll pick up method marks?

for the last question i swear you needed to integrate between 1 and infinity? i did that and it worked out i think...

My dad says that method marks would be given for integrating correctly between the right two numbers, which you didn't do.

So no.