AQA A2 Mathematics MS2B Statistics 2B - 21st June 2016

Original post by tanyapotter

P(X<=0) is the same as P(X=0) - maybe that's where you went wrong?

It's the same thing - damn must've inputted it wrong!

Original post by sam_97

That is the method I used as well. Even if your final answer is incorrect, you will have picked up method marks for definite.

Thanks

I'm just glad that I should be able to get one mark on that question as I had no idea!

Reply 108

sam_97

OP

6

Original post by Suits101

Yup

What did you put for the comment?

I failed to reject Ho, as 2.34 lies outside the critical region. Then I made some comment in context about there being no association between the type of engine and car problems.

Reply 109

Salty carpet

Original post by Suits101

I did that but accepted H0.

You can't accept or reject H1, only accept or reject H0.

Yeah that's what I wrote so it's all good

Reply 110

Suits101

Original post by df97

Hey guys! I had time at the end of the exam so I wrote down most (not all) of the answers I put on my calculator. Obviously some will likely be wrong but here's what I put so we can compare:
1) 0.703, 0.870, 0.133, 0.144, 0.622
2) mean=31.7 sd^2=2024.4
3) 0.35, 0.315, 2.77, 31p, £2.77
4) 0.7, sd(x)=0.0289
5) Z=2.34
6) (can't remember what I put for crit value of island A lizards), Mu(B)=15.1cm
7) For graph I had straight horizontal line from (1, 1/4) to (4, 1/4) and then straight line going down to (6,0) and 0 otherwise.
E(X)=3.04
Let me know if you think any are wrong (i think 1b might be). Thanks! :biggrin:

Hi!

I agree with all but 1(b) I got 0.669

(edited 7 years ago)

Reply 111

Original post by Suits101

This is what I remember and it MAY NOT BE RIGHT

1(a) 0,7029
1(b) 0.669
1(c) 0.1327
1(d) 0.144
1(e) 0.462 (should be 0.622?)

2. Mean = ? s2 = ?

3(a) 0.350
3(b) 0.1575
3(c) Var(x) = 2.7736
3(d) Poisson cannot have an upper limit, people don't borrow books at a constant average rate
3(e)(i) 30.8p
3(e)(ii) 5.27p

4
(a) k = 10
(b) P = 0.70
(c) E(X) = 0.05
(d) Integrate, ans = 1/300
(e) SD(X) = 0.0289

5(a) Test statistic = 2.3386, CV = 2.706 so accept null
5(b) comment

7(a) Draw graph - DENSITY function, so have to differentiate
7(b) 61/6 but I got it wrong

1e was 0.622

3b, you had to do 0.35x0.45x2, as there were 2 combinations
3d. 1st I agree, 2nd point I said P(X=x)=0, which implies e^(-lambda)=0 which is nonsense
2eii. asked fro variance, not sd

Reply 112

Original post by Krithika256

Any predictions for grade boundaries?

65-A 70-A*, more or less the same as 2014 and 1025, maybe closer to the lower of the two

Reply 113

Suits101

Original post by MahuduElec

1e was 0.622

3b, you had to do 0.35x0.45x2, as there were 2 combinations
3d. 1st I agree, 2nd point I said P(X=x)=0, which implies e^(-lambda)=0 which is nonsense
2eii. asked fro variance, not sd

I was going to do that for 3(b) - damn! :smile:

3(e)(ii) - are you sure? Damn!

(edited 7 years ago)

Reply 114

Original post by Salty carpet

Same. Anyone remember their chi^2 value or how they found it? I merged the first two columns and then used Yate's correction... can't remember my value, although I did reject H1

2.3ish and accepted H0, so reject H1 yes (although you should put acceot H0)

Reply 115

2014_GCSE

3

0.703
0.669
0.133
0.144
0.622

mean - 31.7 o^2 - can't remember

0.35
0.158
2.77
30.8
16.7
10
0.7
0.05
1/300
root3 / 60
14.9
18.5

ANSWER DUMP. didn't do the last 4 marker.

Reply 116

lollypandahype

1

I think I said there was association between the engine and mechanical problems, meaning it would be tough to still get the 2 marks for the comment after. I think I mentioned that one of the expected values for Diesel was considerably lower than the actual value and tried to use this to suggest why there was association. I used all the correct terms and stuff, do you think I would still get 2 marks for the comment?

Reply 117