Historically, 5 percent of a mail-order firm’s regular charge-account customers have an incorrect current address in the firm’s computer database. (a) What is the expected number of customer orders...

Historically, 5 percent of a mail-order firm’s regular charge-account customers have an incorrect current address in the firm’s computer database. (a) What is the expected number of customer orders until the first one with an incorrect current address places an order? (b) What is the probability of mailing 30 bills or more until the first one is returned with a wrong address? Hint: use the CDF.