(b) The probability that the salesperson will make a sale to at least one P(make a sale to at least one) = P( (make a sale to one) OR ( make a sale to the second) ) = 0.7 + 0.7 - 0.7*0.7 = 1.4 - 0.49 = 0.91. ANSWER (a) The probability that the salesperson will make a sale to none = complement to the probability of n. (b) = 1 - 0.91 = 0.09. ANSWER