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# OCR MEI - S1 - 20th May 2015 watch

1. (Original post by Kira Yagami)
Did people put there was an upper outlier for the box plot thing or ? 1.5 X 0.3 = 0.45 and add that to Q3 and subrtact it to Q1
Yeah there was no lower outliers but some upper outliers
2. was the cherry question the probability that he has to pick two before he gets a cherry?
3. (Original post by alicec11)
For the football team question the first one was 25C15 right?

And then 13C5 * 12C7 or roughly those figures? I just want to know whether the method was right
Yes, and then divide the second answer by first for the third part ~

25C15 13C8 and 12C7 are the numbers iirc.
4. (Original post by Duskstar)
That's the same I did for the first two questions - the second part was (7*6*5 + 6*5*4 + 4*3*2 + 3*2*1) / (20*19*18)
What's this question you just referred to? I am talking about the 6 marker on A and B probabilities. Are you talking about the (A/B) and (B/A)
5. (Original post by Bobhopkins05)
was the cherry question the probability that he has to pick two before he gets a cherry?
The last part was the probability that he has to pick more than 2 before getting (not cherry).
6. Did people get something like 0.0406 is something for the probablity of X>= to 19 for the hypsothesis test?
7. (Original post by joshgofe)
1/19!!! Yes!! It's just the same as one answer before(cherry 3times in a row) right?? I got that for the last question! Tell me it's right plz
Yes, I'm pretty sure the cherry one was 1/19 (I seem to remember).
8. (Original post by Slenderman)
What's this question you just referred to? I am talking about the 6 marker on A and B probabilities. Are you talking about the (A/B) and (B/A)
Nope - that's the method I used for P(B), which gives what you said I think.
9. conditional probability, one was just 1?
10. (Original post by liverpool2044)
conditional probability, one was just 1?
Yes.
11. (Original post by Duskstar)
The last part was the probability that he has to pick more than 2 before getting (not cherry).
I did 1 minus (6/20 plus (6/20 x 14/20))

would I get any marks for that
I cant remember if I did the 1 minus or not
12. Yep, that's what I got
13. (Original post by liverpool2044)
conditional probability, one was just 1?
One of them was yes, because they'd have to be the same chocolates given that three are orange.
14. (Original post by Bobhopkins05)
what was the actual question for that? How many marks was it?
For the last question, I'll write down what I remember of it:

20 chocolates, 7 O, 6 C, 4 X, 3 Y

First part - 3 people pick a chocolate at random, probability:
A: all pick O
B: all pick the same

Second part - P(A|B) and P(B|A)

Third part - P(A) on two seperate occasions, same situation

Fourth part - probability 1 person gets (not C) in more than 2 picks (with removal)

My method is at the top of page 6 along with the question ^
15. Can someone amazing pls put up an unofficial mark scheme for this exam?? 😊👌
16. (Original post by Duskstar)
Nope - that's the method I used for P(B), which gives what you said I think.
Yeah it does. And for the hypothesis I did like

Ho: p=0.78
H1: p>0.78

where p = is blah blah

and this is the stupid bit. I did the binomial distribution of 19 and I did 1- that answer and got like 99.19% and said it was above 99% as it was a 1% sig test and did the next one to show the next below would be wrong. I got no critical region for the first one and I said that do not reject ho.

On the second one I said do not reject again as my critical region was 20... obviously I know that was wrong. **** -_-
17. (Original post by ¡Muy bien!)
Not sure about the order of questions:
1. Electricity.
2. Sports watched
3. Choosing a 15 people team out of 25 for something?
4.cards
5. 3 dice, highest score
7. Drug hyphothesis
8. Chocolates
Does anyone remember the other questions?
I think 5 was the stem and leaf (about tourists?) and 6 was the dice PDF. The others I think are right (as well as order).
18. The Hypothesis Level value was 0.0461.

1st Q: 0.0461 > 0.01 Accept H0 Reject H1.
2nd Q: 0.0461 < 0.05 Accept H1 Reject H0
19. For the very last question I interpreted it as him having to pick 2 cherries, which would mean that on the third one he could either pick one that he liked or continue picking cherries (hence the more than 2)

So I did (6/20)*(5/19) which gives 3/38, which is the answer quite a few people at my school got.

I also have the question paper with all of my (rounded) answers on in case anyone wants to confer
20. (Original post by Bobhopkins05)
I did 1 minus (6/20 plus (6/20 x 14/20))

would I get any marks for that
I cant remember if I did the 1 minus or not
What I did was 1 - (14/20) - (6/20) * (14/19) - (6/20) * (5/19) * (14/18)

You would get 1 or 2 marks I think (I think it was a 3-marker), depending what exactly you put down.

I'm not 100% sure in what I did - I hope it's correct, but it's possible the third probability wasn't needed, and I haven't had time to think it through properly since the exam lol.

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