Managing Supply Chain and Operations 1st Edition by Thomas Foster ,Scott Sampson,Cynthia Wallin,Scott Webb

Exercise 18

A video store has four checkout lanes. The clerks in each lane have the same abilities, with each clerk being able to check out a customer in 3 ninutes on average. At its busiest times, customers to the video store arrive at the checkout counters at the rate of 50 per hour.
a. What is the average waiting time if all four checkout lanes are being used by the video store?
b. The video store is contemplating closing one of the checkout lanes. If it reduces the number of lanes from four to three, how will customer wait time be affected during the busiest store hours?
c. If the video store reduces the number of checkout lanes from four to three, how will the average processing time (service time) change?