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# Edexcel S2 - 27th June 2016 AM watch

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1. (Original post by economicss)
Is it correct that P(Y> or equal to 7.3) for a binomial distribution would be the same as P(Y> or equal to 8)? Thanks
Correct. This is because if a value is greater than 7.3, then it must be greater than or equal to 8 as there are no values between 7.3 and 8 (and the inequality sign is okay to change, as it would make sense. 8 is > 7.3.
2. (Original post by SeanFM)
Correct. This is because if a value is greater than 7.3, then it must be greater than or equal to 8 as there are no values between 7.3 and 8 (and the inequality sign is okay to change, as it would make sense. 8 is > 7.3.
Thank you!
3. How do you know whether to use a one tail, two tail hypothesis test?
4. (Original post by kkboyk)
How do you know whether to use a one tail, two tail hypothesis test?
Either it will say that specifically, or you'll be testing to see whether the Null hypothesis is different instead of just less than or just greater than

(for 2 tailed)
5. (Original post by kkboyk)
How do you know whether to use a one tail, two tail hypothesis test?
If it specifies whether you're testing if the probability/mean have increased or decreased it's one tailed. If it's testing whether they've changed (generically) then it's two tailed.
6. Here's a question:

If, in the unlikely possibility and more so for my own interest, the probability calculated in a hypothesis test is exactly equal to the significance level (e.g. 0.05), do you reject or accept H0?
7. I just did the specimen paper ( http://tinyurl.com/j26td95 )
and got caught out by question 5b. It said that 'probability for each tail of the region should be as close as possible to 2.5%'
I did the normal thing where you choose the value that 'just about' satisfies the inequality.
It is the first time I have seen such a question, though I haven't done many papers. It's obviously not too difficult, but are there any of papers where this has happened?
8. (Original post by Mattematics)
If it specifies whether you're testing if the probability/mean have increased or decreased it's one tailed. If it's testing whether they've changed (generically) then it's two tailed.
(Original post by Student403)
Either it will say that specifically, or you'll be testing to see whether the Null hypothesis is different instead of just less than or just greater than

(for 2 tailed)
Oh fair enoug, so essentially what the textbook says? Though I dont really understand it :/
9. (Original post by Mattematics)
Here's a question:

If, in the unlikely possibility and more so for my own interest, the probability calculated in a hypothesis test is exactly equal to the significance level (e.g. 0.05), do you reject or accept H0?
reject because it is in the critical region
10. Good luck all. Personally i'm just hoping for a pretty standard paper with no weird and wonderful questions. Think I will get my target A as long as this doesn't go completely tits up ^.^
11. also, do the solomon papers get harder as you go through them or are they all of similar difficulty?
12. (Original post by Ayman!)
Part (c): can anyone explain why {[P(X = 1)P(X = 3)] intersection P(X = 4)} becomes P(X = 1) × P(X = 3) here?

Attachment 557011
what paper is this??
13. Can i double check question 6b with anyone, I think the mark scheme is wrong

https://ef8b5216a7366459ac0f2ce0ac13...%20Edexcel.pdf
14. (Original post by wr123)
Sorry! Just saw this now, I think notifications are messed up. And yes it is in S2 so you are able to the same with any other situation given !
Ok thanks
15. if i have like three functions of CDF
and i want to find the mean which function do i choose to equal to 0.5?
16. (Original post by Patrick Gekko)
also, do the solomon papers get harder as you go through them or are they all of similar difficulty?
Seems pretty uniform tbh.
17. Could someone help me with the last part thanks!

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18. for the last part why do I use the px=n rather than less than or equal to n thanks!

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19. (Original post by RetroSpectro)
Can i double check question 6b with anyone, I think the mark scheme is wrong

https://ef8b5216a7366459ac0f2ce0ac13...%20Edexcel.pdf
I got the answer in the MS
20. Give me an easy and intuitive way to remember the skewness of a PDF please

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