janson's department store in stark, ohio, maintains a successful catalog sales department in which a clerk takes orders by telephone. if the clerk is occupied on one line, incoming phone calls to the catalog department are answered automatically by a recording machine and asked to wait. as soon as the clerk is free, the party who has waited the longest is transferred and serviced first. calls come in at a rate of about 12 per hour. the clerk can take an order in an average of 3.0 minutes. calls tend to follow a poisson distribution, and service times tend to be negative exponential. the cost of the clerk is $8 per hour, but because of lost goodwill and sales, janson's loses about $25 per hour of customer time spent waiting for the clerk to take an order.

a.) what is the average time customers must wait before their calls are transferred to the customer clerk?

b.) what is the average number of callers waiting to place an order?

c.) pamela jansen is considering adding a second sales clerk to take calls? the rate would be the same ($8 an hour). the total cost would be per hour?

d.) by hiring another clerk the total cost savings for jansen's would be per hour