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# OCR MEI - S1 - 20th May 2015 watch

1. (Original post by Duskstar)
I answered the question this way, also. I agree with joe above - the way the question is worded it could be either way, and obviously in the exam I assumed it was this way. I've been thinking about it pretty much all day, and I still can't be 100% I've got my head around it. I'm pretty sure this is the only thing where I could have dropped (big) marks, so I'm alright either way.

Maybe OCR will realise they goofed with the wording and give marks equally to both answers lol.
Here's my two sense: Say he got Cherry Cherry Other - you could say "he had to take more than 2 before getting one he likes"
Then now say he got Cherry Cherry Cherry other - you could say "he had to take MORE THAN 2 BEFORE getting one he likes". Same phrase, different emphasis, so different meaning.
2. (Original post by MathsMaestro)
Is this right for the last question?

1 - [ (14/20 × 13/19 × 12/18) + (6/20 × 14/19 × 13/18) + (6/20 × 5/19 × 14/18) ]

= 0.459649123 = 0.4596 (4 sig figs)
I just put 6/20 * 5/19 = 3/38 = ...... (4.s.f) (can't remember it)

Because I just saw it as P(fail then fail)
3. In general how did everyone find the exam, and what do they think the grade boundaries will be relative to previous years? & how many for full UMS etc
4. (Original post by Eux)
In general how did everyone find the exam, and what do they think the grade boundaries will be relative to previous years? & how many for full UMS etc
I think very similar to last year, has to be >=71/72 for full UMS (not too many trick questions). How did you find it? What you hoping for? I found it relatively easy, 72/72 is still a possibility I think for me
5. (Original post by joe12345marc)
I think very similar to last year, has to be >=71/72 for full UMS (not too many trick questions). How did you find it? What you hoping for? I found it relatively easy, 72/72 is still a possibility I think for me
Agreed, though I left it quite fine with one of the questions regarding time. Some of the probability questions required me to look back at them once I had finished checking but I think they should be correct.
6. (Original post by Eux)
In general how did everyone find the exam, and what do they think the grade boundaries will be relative to previous years? & how many for full UMS etc
Last year for S1 the grade boundary for an A was 61/72. This years paper was quite easy so grade boundaries could be high. My guess is 65/72 for an A this year
7. (Original post by MathsMaestro)
Is this right for the last question?

1 - [ (14/20 × 13/19 × 12/18) + (6/20 × 14/19 × 13/18) + (6/20 × 5/19 × 14/18) ]

= 0.459649123 = 0.4596 (4 sig figs)

yeah i got this
8. (Original post by MathsMaestro)
Last year for S1 the grade boundary for an A was 61/72. This years paper was quite easy so grade boundaries could be high. My guess is 65/72 for an A this year
There's not a chance it will be 65
9. (Original post by MathsMaestro)
Last year for S1 the grade boundary for an A was 61/72. This years paper was quite easy so grade boundaries could be high. My guess is 65/72 for an A this year
(Original post by Lewart)
There's not a chance it will be 65
Agreed, 90% raw is pretty unheard of
10. (Original post by MathsMaestro)
Last year for S1 the grade boundary for an A was 61/72. This years paper was quite easy so grade boundaries could be high. My guess is 65/72 for an A this year
last years was so much easier than this year, the hypothesis test will probably have stumped people as you couldnt use the tables, so no way it will be 65 for an A when last years was 61. Talking out your arse lad
11. (Original post by Duskstar)
Yes, definitely. My teacher told us specifically to answer in terms of H0, because you haven't taken any steps to prove the validity of H1, so the only way you can answer with absolute certainty is with relation to H0.
Ahh. Thank you for the confirmation and clarification! For the second part I said it in both ways from H(o) and H(1) just to be safe! Hoping that method marks from the last questions save me and give me a high UMS mark for this!

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12. (Original post by Setarehp)
I'm guessing it'll be 7-8 marks between each grade boundary, maybe 52-54?
13. For the last question, I said his child didn't pick any sweets because he went and got baked instead hoping i'll get 4/20 overall
14. thank you ^^ (Sorry for the late reply,)
Those videos will be useful for my other exams aas well, Thank you u w u
15. Hypothesis test:

X~B(20, p)
p is the probability that a random person in the population will be treated for a minor illness.

H0 : p = 0.78
H1 : p > 0.78

H1 has this form because researchers hope that the new drug will treat a higher percentage of people than the old drug (something like that can't remember exactly what the context was)

P(X>=19) = 1 - P(X<=18) = 0.046145272 = 0.0461 (3sf)

0.0461 > 1%

So not significant. We cannot reject the null hypothesis. We can conclude that there is not sufficient evidence to suggest that the new drug is more effective than the old drug.

( This is what I got and may be the correct answer. Unfortunately, the formula book only had the probabilities 0.75 and 0.8. To get the accurate value Bcd had to be used on the calculator in Stat mode or Math mode with x set to 18, numtrial set to 20 and p set to 0.78. You then do 1 - the answer to get the probability of P(X>=19) )
For the last question, I said his child didn't pick any sweets because he went and got baked instead hoping i'll get 4/20 overall
Nabeel mate

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17. (Original post by MathsMaestro)
Hypothesis test:

X~B(20, p)
p is the probability that a random person in the population will be treated for a minor illness.

H0 : p = 0.78
H1 : p > 0.78

H1 has this form because researchers hope that the new drug will treat a higher percentage of people than the old drug (something like that can't remember exactly what the context was)

P(X>=19) = 1 - P(X<=18) = 0.046145272 = 0.0461 (3sf)

0.0461 > 1%

So not significant. We cannot reject the null hypothesis. We can conclude that there is not sufficient evidence to suggest that the new drug is more effective than the old drug.

( This is what I got and may be the correct answer. Unfortunately, the formula book only had the probabilities 0.75 and 0.8. To get the accurate value Bcd had to be used on the calculator in Stat mode or Math mode with x set to 18, numtrial set to 20 and p set to 0.78. You then do 1 - the answer to get the probability of P(X>=19) )

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18. (Original post by jpetersgill)

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You still had to put it anyways, it was 8 marks so u gotta include everything
19. (Original post by Darcy1)
You still had to put it anyways, it was 8 marks so u gotta include everything
That's bull**** mate ..

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20. (Original post by jpetersgill)
That's bull**** mate ..

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I know

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