A manager must determine requirements for waiting space for customers. A priority system is used to process customers, who are assigned to one of two classes when they enter the processing center. The highest-priority class has an arrival rate of four per hour; the other class has an arrival rate of two per hour. Both can be described as Poisson-distributed. 

There are two servers, and each can process customers in 15 minutes, on average. 

a. What is the system utilization? 

b. Determine the number of customers of each class that are waiting for service.

 c. Determine the average waiting time for each class. 

d. If the manager could alter the assignment rules so that arrival rates of the two classes were both 3/hour

 what would be the revised average waiting time for each priority class?