The purpose of this exercise is to discuss the situation facing a manager and help her determine how many servers to use and what the characteristics of the system will be. Endeavor Communications, a long distance provider, is reevaluating its account management department for handling customer service questions and requests. During the 6:00 pm to 10:00pm time period, past data show that calls to the account management department occur at an average rate of one call every 6.5 minutes. A study of past service times indicate that the average time to process a caller's question/request is 4.3 minutes. Like other phone systems, when a call comes in and all the servers are busy, the caller hears a message telling them to hold until the next server is available.
Top management at Endeavor Communications understands that the staffing decision involves the analysis of trade-offs. Increasing the number of servers will reduce the waiting times and increase the probability of immediate service at a higher cost with more idle time for the servers. Management has decided that the goal of the account management department is to immediately answer and service at least 90% of the incoming calls during the busiest time period of 6:00 to 10:00pm. They have asked you to determine the staffing level that will help them meet this goal. Also, they'd like you to provide your own recommendations.