SOLUTION: Data collected from past records reveals that 9% of the returns prepared by Wallen have been selected for audit by the IRS. Today, Wallen has six new customers. Assume the chances

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Question 342216: Data collected from past records reveals that 9% of the returns prepared by Wallen have been selected for audit by the IRS. Today, Wallen has six new customers. Assume the chances of these six customers being audited are independent. My question is this: What is the probability that exactly one of the six new customers will be selected for audit?
I already have figured out the probability that all six new customers will be selected for audit (5.0*10^-7), and the probability that none of the six new customers will be selected for audit (.568). I am not sure if I need to use the answers from these 2 problems or not to figure out the answer to this question. I know the answer to my question (.337), but I do not know how to get to it.
Answer by scott8148(6628) About Me  (Show Source):
You can put this solution on YOUR website!
this is a binomial expansion probability

p = probability of audit = .09

n = probability of no audit = .91

the expansion is ___ (p + n)^6

the pertinent term is ___ 6C5(pn^5)

6 * .09 * .91^5 = .336977 (approx)