A notebook computer dealer mounts a new promotional campaign. Purchasers of new computers may, if dissatisfied for any reason, return them within 2 days of purchase and receive a full
refund. The dealer estimates that 18% of all purchasers will
, indeed, return computers and obtain refunds. Suppose that 50 computers are purchased during the campaign period. Find the mean
and standard deviation of the number of these computers that will be returned for refunds.