Question

In testing a new drug, researchers found that 1% of all patients using it will have a mild side effect. A random sample of 12 patients using the drug is selected. Find the probability that:

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

Answer 1

You can use a binomial probability table, which is the easiest way to do this problem.

For A, find P(1).
For B, find P(0), then subtract that value from 1.

To find the probabilities in the table:
For A, n = 12, p = .01, x = 1
For B, n = 12, p = .01, x = 0

I'll let you take it from here.