Question: A vending machine dispenses hot coffee. The service time is 30 seconds per cup, and is assumed to be constant. Customers arrive at a rate of 80 per hour, Poisson distributed. Determine:

a. The average number of customers waiting in line.

b. The average time customers spend in the system.

c. The average number of customers in the system.

d. The average cost per hour of the system if the operating costs of the machine are $20 per hour and the cost of waiting is estimated to be $30 per hour.