A small warehouse supplies local businesses with paper products. Trucks pull up to the loading bays; the driver places an order and then waits for the order to be gathered by the warehouse worker who...

A small warehouse supplies local businesses with paper products. Trucks pull up to the loading bays; the driver places an order and then waits for the order to be gathered by the warehouse worker who drives a forklift truck. There are currently four loading bays, and when they are full, trucks wait in the parking lot next to the warehouse until a loading bay is available. The warehouse is open from 7 a.m. to 4 p.m., Monday through Friday. Trucks arrive throughout the day. The warehouse has two forklift drivers who pick orders one at a time on a first-come-first-served basis. The truck drivers load their own orders and then leave the loading dock. The warehouse company is interested in whether it would be more effective to add another forklift driver or another loading bay, or if either option is substantially better than the current service. The performance measures it is interested in include the average number of trucks waiting in the parking lot and the total time a truck spends at the warehouse. It also wants to know the utilization of the forklift drivers. Data collected on the warehouse operation show the following:

• The arrival rate of trucks is 6.5/hour, with the time between arrivals being exponentially distributed.

• The mean time for a forklift to fill an order is 15 minutes. The distribution is normal with standard deviation 1.5 minutes.

• The time required for a driver to load an order is well modeled as an Erlang random variable with mean 15 minutes and 3 phases.