Ships arrive at a busy seaport 8 per day for loading/unlading and its unloading facilities take 4 hours, on an average, to unload a ship. Assume multiple M/M/1 systems. The cost of unloading and ship's time in the port is $20,000 and $35,000 per day, respectively. Determine the optimal number of unloading facilities to minimize the total cost of unloading and ship's waiting time. (30) Hint: Compute the cost for service facilities, ship's time, and the total cost. Assume that arrival rate is equally divided among unloading facilities