4. ) Auto vehicles arrive at a petrol pump, having one petrol unit, in Poisson fashion with an average of 10 units per hour. The service time is distributed exponentially with a mean of 3 minutes. Find the following: i. Average number of units in the system ii. Average waiting time iii. Average length of queue iv. Probability that a customer arriving at the pump will have to wait v. The utilization factor for the pump unit vi. Probability that the number of customers in the system is 2.