11. Consider the queueing system for the walk-in services of a post office. Customer arrive at an average rate of 30 per hour. The average rate is 8 customers per hour per server. There are 4 servers. Customers join a single queue and get served by one of 4 available servers. The customers get served first-come-first-served (FCFS). What is the probability that an arriving customer finds the post office empty?

1. The answer cannot be determined using the available information

2. 0.0625

3. 1.0000

4. 0.0066

5. 0.8650

12. Consider the queueing system for the walk-in services of a clinic. The average time between two consecutive arrivals is 3 minutes. Customers join a single queue and get served by one of 3 available servers. A server can serve 7 customers per hour on the average. The customers get served first-come-first-served (FCFS). What is the average number of customers waiting in the queue at any point in time? Mark the nearest answer.

1. 1

2. 18

3. 21

4. 30

5. 2