Trucks arrive at a warehouse at a rate of 6 per hour during business hours. Crews at each dock can unload the trucks at a rate of 2 per hour. Each dock is staffed with two workers, i.e., the ratio of crews to docks is 2:1. Recent changes in wage rates have caused the warehouse manager to reexamine the question of how many crews and docks to use. The new rates are crew and dock cost is $200 per hour; truck and driver cost is $150 per hour. Find the optimal number of dock and crews. Assume that arrival and service rates are Poisson.