Ambulances are dispatched at a rate of one every 15 Â± lO minutes in a large metropolitan area. Fifteen percent of the calls are false alarms, which require 12 Â± 2 minutes to complete. All other calls can be one of two kinds. The first kind are classified as serious. They constitute 15% of the non-false alarm calls and take 25 Â± 5 minutes to complete. The remaining calls take 20 Â± 10 minutes to complete. Assume that there are a very large number of available ambulances, and that any number can be on call at any time. Simulate the system until 500 calls are completed.