Trucks arrive at a warehouse at a rate of 12 per hour during business hours. Crews can unload the trucks at a rate of 2 per hour. Recent changes in wage rates have caused the warehouse manager to reexamine the question of how many crews to use as that will affect their profitability and productivity. The new rates are: Crew and dock cost is $90 per hour; truck and driver cost is $140 per hour. The crew and dock cost represents the server cost and the truck and driver cost represents the waiting cost. How many crews does the warehouse need to minimize the total cost per hour? Set up a model in Excel and find the optimal number of crew members needed to perform the operation with a minimum cost.