For any one of the individual s* queues, what is the utilization of the server at the optimal staffing level (optimal utilization)? a. 0.75 b. 0.80 c. 0.60 d. 0.90 Considering any one of the individual s' queues, derive the expected number of customers waiting in line a. 3.2 customers b. 8.1 customers c. 2.25 customers d. 0.9 customers