Schips, Inc., a large department store, has recently been experiencing some problems in its receiving and shipping department because of the substantial growth in the store's sales volume. Currently, the store's truck dock has only one dock crew who handles one truck at a time.

The manager is considering adding more dock crews so that multiple trucks would be loaded and/or unloaded simultaneously. The manager has collected the following data:

• Truck arrivals are not scheduled and occur in an unpredictable fashion at an average of 24 per 8-hour day.
• When working continuously, each dock crew can service an average of 4 trucks per hour.
• Suppose that the Schips trucks are operated at a cost of $25 per hour and that a dock crew is paid a total of $30 per hour.

1. How many dock crews should be hired to minimize the total cost for Schips?