You are Here: Home >< Maths

# Ocr mei statistics 1 exam thread (24/05/13) watch

1. (Original post by Blobar)
You needed to times the first answer by 3 at the end as there are 3 different ways of getting that.
Ah damn, I really wasn't sure. I should hopefully get 2 of the marks though. And maybe some method marks for part ii).
2. (Original post by jonny7bell)
A few papers I have done on S1 have got to 53 as an A. A few have been rather high, but I think this will probably be around 55-57 for an A, as Q2 and the last question probably threw a few people off. So I would still say a mid B.
I'd say whoever gets 50 will be lucky to get a B, rarely do I see past papers which dip below 57 and some are even higher than that. There's always hard questions on the papers even where the grade boundaries are 57 so I think it will be about 57 +/- 1
3. jonny bell i did 5/10 x 4/9 x 5/8 x 3! because theres 3 different ways they could have been picked
4. The last part of the last question was:

P( BULL AND BULL AND BULL) + P( MISS AND MISS AND MISS AND BULL AND BULL AND BULL)

All in all, a really good exam i thought
5. (Original post by lorobolorolo)
I'm not completely sure, but I think question 3 was the question on the bag of flours which weighed 1.5kg or something like that. And then they asked u to calculate something about 50 bags and then there was the question about 20 in a box and whats the probabilty of at least 1 bag being underweight. Correct me if i'm wrong.
Yeah, question 3 was the binomial one.

"The weights of bags of a particular brand of flower are quoted as1.5kg. In fact, on average only 10 percentage of the bags are underweight"

i) Find the problem of exactly 5 bags out of 50 being underweight
ii_ Find the probability that at least 1 bag out of 20 is underweight
iii) A crate contains 48 boxes. Find the expected number of boxes in the crate which contain at least 1 underweight bag.
6. u mean 3! not 3 blobar
7. (Original post by Mahinder)
jonny bell i did 5/10 x 4/9 x 5/8 x 3! because theres 3 different ways they could have been picked
Yeah that makes more sense, ffs.
8. (Original post by Blobar)
I'd say whoever gets 50 will be lucky to get a B, rarely do I see past papers which dip below 57 and some are even higher than that. There's always hard questions on the papers even where the grade boundaries are 57 so I think it will be about 57 +/- 1
S1 papers are somewhat an exception, "speaking statistically, the median is around 56/57 for an A, however there have been a few outliers of around 53 for an A"

Sorry I had to do this.
9. Bricking it for what I get in maths now,Honestly if luck decided to enlighten me after all the hours I've put in in these exams,ill get my A with at A B C in the three exams , the worst is a D for me,never going to look at maths related threads on here because it just messes your mind up.Having said that I have to thank everyone who helped me on here and the mega a level maths thread.good luck everyone who has forthcoming exams.If only the amount of work you put into exams decided your grades eh ?

Posted from TSR Mobile
10. Did everybody find themselves rejecting the test on question 5? I got P(x<=13)=0.1316.0.05 so not enough evidence.
11. (Original post by Mahinder)
jonny bell i did 5/10 x 4/9 x 5/8 x 3! because theres 3 different ways they could have been picked
Sounds good, but you would just times by 3, not 3!

it was : ( 5/10 x 4/9 x 5/8 ) + ( 5/10 x 4/9 x 5/8) + ( 5/10 x 4/9 x 5/8 )

So basically just: 3 x ( 5/10 x 4/9 x 5/8 )

if you were to times it by 3! it would be: 6 x ( 5/10 x 4/9 x 5/8 ) [which is incorrect sorry sorry sorry ]
12. (Original post by jonny7bell)
What did everybody do for question 2? That was the only question I found rather hard.

I did:

i) 5/10*4/9*5/8=5/36
ii) I tried to binomial distribute it and got 0.0096, no idea if it was right though.
can someone remind what this question was about???
13. so for question 3 i did

x-b(50, 0.1)
p(x=5) = 50c5 x0.1^5 x 0.9^45

ii)
x-b(20,0.1)
p(x>=1)=1-p(x<=0) = 0.874

then it was expectation question i think so it was 48 x 0.874
14. also, critical region was X>=15

right?
15. (Original post by Mahinder)
so for question 3 i did

x-b(50, 0.1)
p(x=5) = 50c5 x0.1^5 x 0.9^45

ii)
x-b(20,0.1)
p(x>=1)=1-p(x<=0) = 0.874

then it was expectation question i think so it was 48 x 0.874
that's correct
16. (Original post by Mahinder)
so for question 3 i did

x-b(50, 0.1)
p(x=5) = 50c5 x0.1^5 x 0.9^45

ii)
x-b(20,0.1)
p(x>=1)=1-p(x<=0) = 0.874

then it was expectation question i think so it was 48 x 0.874
**** do you lose marks for not writing this even if you get the answer?
17. (Original post by Mahinder)
so for question 3 i did

x-b(50, 0.1)
p(x=5) = 50c5 x0.1^5 x 0.9^45

ii)
x-b(20,0.1)
p(x>=1)=1-p(x<=0) = 0.874

then it was expectation question i think so it was 48 x 0.874
I got 0.8784 for ii), then 42.2 for iii).
But assuming you made a typo, that is what I got.
18. (Original post by juniorx)
**** do you lose marks for not writing this even if you get the answer?
19. Did we all accept h0 for the hypothesis test ?

Posted from TSR Mobile
20. (Original post by tumblrgirl)
me too, I did (5C2 x 5C1)/10C3 and i got 5/12 as my answer
I did the same, There was wayyy too much probability in this paper

TSR Support Team

We have a brilliant team of more than 60 Support Team members looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.

This forum is supported by:
Updated: February 14, 2014
Today on TSR

### Three reasons you may feel demotivated right now

...and how to stay positive

### Can I get A*s if I start revising now?

Discussions on TSR

• Latest
Poll
Useful resources

Can you help? Study help unanswered threadsStudy Help rules and posting guidelinesLaTex guide for writing equations on TSR

## Groups associated with this forum:

View associated groups
Discussions on TSR

• Latest

The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE