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 I need help with the second part please!!
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jenzy569
Junior Member

USA
4 Posts

Posted - 10/26/2011 :  18:24:44  Show Profile  Reply with Quote
In testing a new drug, researchers found that 10% of all patients using it will have a mild side effect. A random sample of 14 patients using the drug is selected. Find the probability that:

(A) exactly two will have this mild side effect
(B) at least three will have this mild side effect.

N = 14 (14 patients)
X = 2 (exactly 2 will have this mild side effect)
P = 0.10 (prob. of all patients using it will have a mild side effect; success)
Q = 0.90 (1 - p = 1 - 0.10 = 0.9)

(A)
= 14!/(14-2)!2! (0.10)(0.90)14-2^2
= 14*13*12!/12!2*1(0.10)(0.90)12^2
= 14*13/2*1(0.01)(0.28)
= 182/2(0.01)(0.28)
= 91(0.01)(0.28) = 0.25 or 25%

But I'm not sure how to do part B.....please help!!
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royhaas
Moderator

USA
3059 Posts

Posted - 10/27/2011 :  08:59:01  Show Profile  Reply with Quote
"At least three" is the complement of "No more than two".
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