Question

. In testing a new drug, researchers found that 20% of all patients using it will have a mild side effect. A random sample of 15 patients using the drug is selected. Find the probability that:

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

Answer 1

Try a binomial probability table or use a binomial probability function, which is this:

P(x) = (nCx)(p^x)[q^(n-x)]

For (A)
x = 3
n = 15
p = .20
q = .80 (q is 1-p)

For (B)
Using a table might be easier for this one. Find P(0), P(1), P(2), P(3), P(4), and P(5). Add together, then subtract from 1 for your probability.

I'll let you take it from here.