A telephone in a police precinct is used for both emergency calls and personal calls. Personal calls are on a first-come, first-served basis and are made at a rate of one every 5 +/- 1 minutes. Emergency calls have priority and can preempt other calls. They arrive at a rate of one every 15 +/- 5 minutes. Emergency calls take 3 +/- 1 minutes to complete while personal calls take 2 +/- 2 minutes. Twenty percent of the people using the phone on a non-emergency basis wish to make another call as soon as possible, but they are given the lowest priority for their second call. Simulate until 200 calls of all types have been completed. Estimate the phone utilization.