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 All Forums  Homework Help Forums  Probability and Statistics  I need help with the second part please!! New Topic  Reply to Topic  Printer Friendly
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jenzy569
Junior Member

USA
4 Posts

 Posted - 10/26/2011 :  18:24:44 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)²(0.90)14-2^2= 14*13*12!/12!2*1(0.10)²(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!!

royhaas
Moderator

USA
3059 Posts

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