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statistics help

Hello, for 5d on this paper, the mark scheme refers to the normal distribution and n being large and p close to 0.5, yet the question only mentions the sample size and probability, so surely it would be binomial? And for question 6, do you assume that a and b are independent. the mark scheme uses the formula for a and b if they are independent, but the question doesn't mention this? Many thanks https://crashmaths.com/wp-content/uploads/2018/09/A2-M-BRONZE-P3-A.pdf
Original post by Bertybassett
Hello, for 5d on this paper, the mark scheme refers to the normal distribution and n being large and p close to 0.5, yet the question only mentions the sample size and probability, so surely it would be binomial?


Yes, it would be binomial (do you have the tables for n=200?), but the question asks you to use a suitable approximation.


And for question 6, do you assume that a and b are independent. the mark scheme uses the formula for a and b if they are independent, but the question doesn't mention this? Many thanks https://crashmaths.com/wp-content/uploads/2018/09/A2-M-BRONZE-P3-A.pdf


No, you cannot assume A,B are independent. You may be able to show it, but in this case it's not true. You need to post the markscheme.
ok thanks. but for the probability q how do you then work it out?
Original post by ghostwalker
Yes, it would be binomial (do you have the tables for n=200?), but the question asks you to use a suitable approximation.



No, you cannot assume A,B are independent. You may be able to show it, but in this case it's not true. You need to post the markscheme.
Original post by Bertybassett
ok thanks. but for the probability q how do you then work it out?


Don't know which question/part you're refering to, and you've not posted the markscheme.
question 6 (was clearly in original post) and dont have the ms
Original post by ghostwalker
Don't know which question/part you're refering to, and you've not posted the markscheme.
Reply 5
Original post by ghostwalker
Yes, it would be binomial (do you have the tables for n=200?)

Calculators are used now so there’s no limit really to what can be calculated.
Original post by Bertybassett
question 6 (was clearly in original post) and dont have the ms


Which part?

And you mentioned the markscheme uses the formula for A,B independent, implying you have access to it. If not, are you sure it says that?
(edited 4 years ago)

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