Ashley’s department store in Kansas City maintains a successful catalog sales department in which two clerks take 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 that has waited the longest is transferred and answered first. Calls come in at a rate of about an average 15 minutes. The clerk is capable of taking an order in an average of 15 minutes. Calls tend to follow a Poisson distribution, and service times tend to be exponential. The clerk is paid $15 per hour, but because of lost goodwill and sales, Ashley’s losses about $30 per hour of customer time spent waiting for the clerk to take an order.
1. lambda_____________/hour and \mu____________ /hour
2. What is the probability there is no customer in the line?
3. What is the average number of callers waiting to place an order?
4. What is the total cost per hour?