A large industrial pier has two cranes that load container ships. Trucks arrive in a single line and then go to the next available crane when it is clear to do so. The arrival rate of the trucks is Poisson distributed. They arrive at a rate of 20 trucks per hour. Each crane works independently and can attach to the truck-pulled container and place it on the container ship in 4.8 minutes, on average. Crane loading activities follow an exponential distribution How long is the line of trucks on average, not including the trucks being unloaded? If a third crane were added, how would the average length of the line change