319. A company is marketing an investment opportunity to four potential customers. The
company believes that its probability of making a sale is 0.7 for each of the first three
customers but that it is only 0.2 for the fourth customer. The customers' purchases are
independent of one another.
Calculate the probability that at most two customers purchase the investment.
(A) 0.18
(B) 0.39
(C) 0.57
(D) 0.71
(E) 0.82