Exhibit 13-2An Oil-Change Facility Serves Customers That Enter at a Rate

Essay

Exhibit 13-2An oil-change facility serves customers that enter at a rate of 8 per hour. There are five servers available to perform oil changes for entering customers. Customers wait in a single line and enter the facility, in first-come-first-serve fashion, to the first of the five servers who is available. Each server can change the oil of one customer's car every 30 minutes on average.
-Refer to Exhibit 13-2. How many of the servers are busy on average?