An automated car wash with a constant service time of 5 min. Cars arrive at rate = 9

per hour with Poisson distribution. The service cost (lease and employee wages) costs

975 per week and it is estimated that the waiting cost is

400 per week.

(a) What type of queue would best model the current system?

(b) What is the average length of waiting line and average waiting time?

(c) What is the current systems weekly total costs?

(d) The owner of the car wash is considering upgrading the car wash to a newer one

that has a service time of 4 min but has a service cost of

1100 per week. Should

they make the switch?