Posted by **Jen** on Wednesday, October 26, 2011 at 6:19pm.

3. 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.

I got this for (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 (B)

PLZZZZZ HELP!!!

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**MathGuru**, Thursday, October 27, 2011 at 5:28pm
A looks OK!

For B, use the same process. Since the problem says "at least 3" you will have to determine P(0), P(1), P(2). You already have P(2) from part A. Add P(0), P(1), and P(2) together. Then subtract that value from 1 for your probability.

I hope this helps.

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**spam**, Friday, September 26, 2014 at 7:58pm
SPAMA GUY!!! LOLOLATRA HAIL BIN LADIN!

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