(This problem description is for Questions 14, 15, 16, 17, 18, 19, 20, 21, 22) Tom, a college student, has taken a job as customer service representative in the computer department of a local department store to pay his rent. His only responsibility is to answer telephone calls for the department, most of which are inquiries about store hours and product availability. As Tom is the only person answering calls, the manager of the store is concerned about queuing (or waiting line) problems. Tom gets $15 per hour. Currently, the computer department receives an average of one call every 4 minutes, with standard deviation in this inter-arrival time of 4 minutes. Tom requires an average of 3 minutes to handle a call. The standard deviation of this activity time is 3 minutes. Assume that there is no limit on the number of customers that can be on hold, and customers do not hang up even if they are forced to wait for a long time. The telephone company charges $5.00 per hour for telephone lines whenever they are in use (either while the customer is in conversation with Tom or on hold because Tom is talking to some other customer). Find the total time a customer spends on average including waiting time and service time. 20 minutes 12 minutes 11 minutes 15 minutes 9 minutes