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

1. Just realised my mistake i did , 0.5 not 0.05
2. Unofficial MS:
1i) mean = 249.4 sd = 14.475
1ii) new mean = 209.46 new sd = 13.0275

2i) 5/12
2ii) 0.1989

3i) 0.185
3ii) 0.8784
3iii) 42.16

4i) prove 1/20th.
4ii) e(x)= 1507.5 var(x) = 445511.25

5i) probability of right or wrong is 0.5 as the e(x) is 0.5 (guess of 2 items).
5ii) Accept null hypothesis, critical region 15-20.

6i) median = 3.32 q3= 3.71 q1=2.83 iqr= 0.88
6ii) outlier 1.5(0.88) +/- median. Don't discount.
6iii) median = 3.5 q3 = 3.85 q1= 3.14 iqr= 0.71
6iv) Boys have a greater avg weight, girls have more variance in the weights.
6v) 0.0018

7i) Draw diagram
7ii) A: 0.1878 B: 0.1541 C: 0.8242
7iii) 0.0056
3. Could u please post question number 6. I need to check the cumulative frequency diagram.
4. (Original post by hoa123)
UNOFFICIAL MARK SCHEME

vi) (8/200)x(7/199). You can probably use any values from 7-10/200 (it depends how you read the graph). [3]
For question 6 part vi) is it wrong if I multiplied the answer by 2. So what I did was:
(8/200)x(7/199) *2

I did that because there are two ways of picking the two boys. If that is wrong could someone please explain to me why thats wrong
57-A- or higher
52-B
47-C
42-D
What do you guys think... realistic enough or a bit higher.
6. (Original post by Ravs101)
57-A- or higher
52-B
47-C
42-D
What do you guys think... realistic enough or a bit higher.
58/52/46/40/36
7. I really messed up question 2 I did 5/10*4/9*5/8 and left it as 5/36. Do you get error carried forward marks on these maths papers? Because I also made a mistake on question 6 working out the first upper quartile wrong. Hate realising mistakes when you've left the exam it felt like it was okay as well!!

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8. for 2 ii) I did (5/12 x 5/12 x 5/12 x 7/12) + ( 5/12 x 5/12 x 5/12 x 5/12)
9. (Original post by Mathsz0r)
Unofficial MS:
1i) mean = 249.4 sd = 14.475
1ii) new mean = 209.46 new sd = 13.0275

2i) 5/12
2ii) 0.1989

3i) 0.185
3ii) 0.8784
3iii) 42.16

4i) prove 1/20th.
4ii) e(x)= 1507.5 var(x) = 445511.25

5i) probability of right or wrong is 0.5 as the e(x) is 0.5 (guess of 2 items).
5ii) Accept null hypothesis, critical region 15-20.

6i) median = 3.32 q3= 3.71 q1=2.83 iqr= 0.88
6ii) outlier 1.5(0.88) +/- median. Don't discount.
6iii) median = 3.5 q3 = 3.85 q1= 3.14 iqr= 0.71
6iv) Boys have a greater avg weight, girls have more variance in the weights.
6v) 0.0018

7i) Draw diagram
7ii) A: 0.1878 B: 0.1541 C: 0.8242
7iii) 0.0056
for 2 ii) I did (5/12 x 5/12 x 5/12 x 7/12) + ( 5/12 x 5/12 x 5/12 x 5/12) = 0.0723
im pretty confident with that so who has made the error
10. I got Q2 right?!?! I think I'm going to pee.

(Original post by Ravs101)
57-A- or higher
52-B
47-C
42-D
What do you guys think... realistic enough or a bit higher.
I don't think an A will be any higher than that. January 2013 was 57 and that was the easiest S1 paper I completed.
11. (Original post by zangorou)
I got Q2 right?!?! I think I'm going to pee.

I don't think an A will be any higher than that. January 2013 was 57 and that was the easiest S1 paper I completed.
how many marks do you reckon you got out of 72 ???
12. (Original post by Law-Hopeful)
For question 2ii I forgot to multiply by 4!... How many marks do you think I will lose (out of 4) for that as the rest of my answer was fine?
Crap I just realised i did the same mistake, id reckon we would lose 2 our of the 4
13. (Original post by Mo_maths)
Crap I just realised i did the same mistake, id reckon we would lose 2 our of the 4
Why did we have to multiply by 4?!

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14. (Original post by x-Sophie-x)
Why did we have to multiply by 4?!

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5/12 ^ 4 + 4C3 x (5/12 ^3 x 7/12)
15. You cant pick 8/199 first because you start with 200. And there cant be 7/200 if theres 8/199.
16. I failed..
17. I forgot square root the sd so how many marks will i lose, left my answer as 209.46. when I coded I also used 209.46
18. (Original post by Ravs101)
57-A- or higher
52-B
47-C
42-D
What do you guys think... realistic enough or a bit higher.
I thought it was the hardest S1 paper I've seen. Maybe it was because it was because it was the real one but i dont think it would be that high. I think it could be lower than that
19. (Original post by charliekeki)
I thought it was the hardest S1 paper I've seen. Maybe it was because it was because it was the real one but i dont think it would be that high. I think it could be lower than that
It really wasn't, if you'd done all the past papers you'd have seen how straight forward it was. There wasn't anything different to previous papers.
20. (Original post by Mo_maths)
how many marks do you reckon you got out of 72 ???
I definitely lost 3 on the last Q, maybe 4. So maybe 66/65, hopefully!

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