The mean inter-arrival times of professors and students to a restaurant inside the campus is 4 and 2 minutes, respectively. There are two people serving the customers at the place where the foods are selected by the customers. If both servers are busy, a newly arrived customer wait in the queue. The mean service time is 2 minutes. a. Is this queue stable? If so, solve below questions. b. Find the expected waiting time of customers in the queue in steady state. C. Find the expected waiting times of professors and students in the queue, if professors have the (nonpreemptive) priority. d. Find the expected waiting times of professors and students in the queue, if students have the (nonpreemptive) priority.