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# June 22nd 2005 - The Official S2 Discussion Thread! watch

1. (Original post by Kiril)
What if I have used the normal approximation, would I have lost marks?
I'm not sure how the mark scheme would be on that
2. ahhh pooo, 1-5 finished in about 25mins, froze on 6+7
3. (Original post by cherc2005)
For the last question,
did you put for:
(a) X~B(20, 0.75)
(b) P(x = 6) did you use the binomial fomula?

(c)... firstly what did people put as their H0 and H1
did people reject h0 or not reject h0?
and what did people get as the probabilty?
i think i did the working out wrong, but i stated both H1 and H0 and said you dont reject H0. if you DONT reject H0, and this is correct but your markings wrong, given everything else in the question, would i get any marks?
Yes, I got that for part a.

Yes, I used the binomial formula giving my answer to 3.s.f

I never rejected H0 for part C. I think i got that the probability of there being 13 cured patients was about 0.2 and 0.2>0.05 so keep H0
4. (Original post by cherc2005)
For the last question,
did you put for:
(a) X~B(20, 0.75)
(b) P(x = 6) did you use the binomial fomula?

(c)... firstly what did people put as their H0 and H1
did people reject h0 or not reject h0?
and what did people get as the probabilty?
i think i did the working out wrong, but i stated both H1 and H0 and said you dont reject H0. if you DONT reject H0, and this is correct but your markings wrong, given everything else in the question, would i get any marks?
H0: p=0.25
H1: p>0.25
i got P(X»7) = 1 - P(X«6) = 1-0.7858=0.2142

its way more than 5%...so not enough evidence to reject H0

n in (b) yes, i used the binomial formula
5. (Original post by tobyclark)
you should only use normal where p is close to 0.5, so no

...no as in I would have lost marks if I have used the Normal approx or no as in I wouldn't have?
6. Question -

If I put the following...

H0 : p = 0.75

H1 : p < 0.75

Then proceeded to test using B(20, 0.25), would I have lost marks?
7. (Original post by seankhn)
Question -

If I put the following...

H0 : p = 0.75

H1 : p < 0.75

Then proceeded to test using B(20, 0.25), would I have lost marks?
i think not
8. (Original post by seankhn)
Question -

If I put the following...

H0 : p = 0.75

H1 : p < 0.75

Then proceeded to test using B(20, 0.25), would I have lost marks?
Me 2, I am looking for the same answer...although I have later on used normal approx, because it was an awful lot of work to work with value of P which is not in the tables
9. (Original post by seankhn)
Question -

If I put the following...

H0 : p = 0.75

H1 : p < 0.75

Then proceeded to test using B(20, 0.25), would I have lost marks?
no you havent
10. Oh, changing the subject with a worthwhile distraction:

Did anyone notice the typo on the paper? It was quite subtle, and I suppose they could say intentional, but much glory to be basked in for the person who says it first!

(This is coming from the person who neglected to spot that a question asked for an answer to 2 dp!!!)
11. (Original post by hajira)
i think not
Wicked. I've seen so many times in the past where they've had p = blah as their hypothesis and then tested using an approximation or whatever.

I hope those edexcel *******s don't taint me with their pickyness.
12. (Original post by seankhn)
Question -

If I put the following...

H0 : p = 0.75

H1 : p < 0.75

Then proceeded to test using B(20, 0.25), would I have lost marks?
same i did this too, but, i think i mucked it up after that.
but i said "do not reject H0" and said blah blah because of insufficient evidence etc.

do you think given i put H1 and H0 and also said reject h0 and also i think i might have put some working about 0.25 and reversing.
do you think i stand a chance of getting any marks at all?
13. How many marks for the last question in total..?
14. I did not spot it either......damn........
15. (Original post by pumpkinstein)
Oh, changing the subject with a worthwhile distraction:

Did anyone notice the typo on the paper? It was quite subtle, and I suppose they could say intentional, but much glory to be basked in for the person who says it first!

(This is coming from the person who neglected to spot that a question asked for an answer to 2 dp!!!)
lol..this shud b interesting
wat was it??
16. (Original post by cherc2005)
same i did this too, but, i think i mucked it up after that.
but i said "do not reject H0" and said blah blah because of insufficient evidence etc.

do you think given i put H1 and H0 and also said reject h0 and also i think i might have put some working about 0.25 and reversing.
do you think i stand a chance of getting any marks at all?
Yes, very much so, even if you get the sums wrong, for stating the hypotheses and then making an acceptance/rejection based on YOUR result, you'll at least get something.
17. (Original post by Kiril)
How many marks for the last question in total..?
6marks for the (c)
4 marks for (d)

and i think (a)(b) were 2marks each = 4marks between the first 2 parts

so 14 altogether.
18. i have always hates s2 and this exam was no excpetion....i'm pretty screwed
19. what were Question 2,3,4,5 about?

i cannot remember anything....
20. what is the definition for sampling distribution

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