A Discrete-Event Queuing Model


You are an MIS manager for a large multinational firm, about to install a database server that will be constantly queried by employees around the globe.  You expect the queries to arrive at an average rate of 1 per second, and the time between successive queries should be well-modeled by an "exponential" random variable.

For this task, you are considering two possible models of server computer, "server 1" or "server 2".  You estimate that the time server 1 will take to answer a query is uniformly distributed between 0.4 and 1.4 seconds.  Server 2 is about 25% faster: you estimate its time to answer a query to vary uniformly between 0.3 and 1.1 seconds.

If the server is busy when a query arrives, the query is placed on a wait queue.  Waiting queries are answered in the order they are received.

Since server 2 is considerably more expensive, you'd like to estimate the difference in the quality of service provided by the two servers.  Simulate two minutes of operation of each server, and estimate the average number of queries in the system and the average time employees will have to wait for answers to their queries.