7 (Requires use of a spreadsheet or LINGO) The machine repair model may often be used to approximate the behavior of a computer’s CPU (central processing unit). Suppose that 20 terminals (assumed to always be busy) feed the CPU.

After the CPU responds to a user, he or she takes an average of 80 seconds before sending another request to the CPU

(this is called the think time). The CPU takes an average of 2 seconds to respond to any request. On the average, how long will a user have to wait before the CPU acts on his or her request? How will your answer change if there are 30 terminals? 40 terminals? Of course, you must make appropriate assumptions about exponentiality to answer this question.