Airline ticket counter-At an airline ticket counter, the current practice is to allow queues to form before each ticket agent. Time between arrivals to the agents is expo- nentially distributed with a mean of 5 min. Customers join the shortest queue at the time of their arrival. The service time for the ticket agents is uniformly distributed between 2 and 10 min:

a. Develop an ExtendSim model to determine the minimum number of agents that will result in an average waiting time of 5 min or less.

b. The airline has decided to change the procedure involved in processing custom- ers by the ticket agents. A single line is formed, and customers are routed to the ticket agent who becomes free next. Modify the simulation model in part (a) to simulate the process change. Determine the number of agents needed to achieve an average waiting time of 5 min or less.

c. Compare the systems in parts (a) and (b) in terms of the number of agents needed to achieve a maximum waiting time of 5 min.

d. It has been found that a subset of the customers purchasing tickets is taking a long period of time. By separating ticket holders from non-ticket holders, management believes that improvements can be made in the processing of customers. The time needed to check in a person is uniformly distributed between 2 and 4 min. The time to purchase a ticket is uniformly distributed between 12 and 18 min. Assume that 15% of the customers will purchase tickets and develop a model to simulate this situation. As before, the time between all arrivals is exponentially distributed with a mean of 5 min. Suggest staffing levels for both counters, assuming that the average waiting time should not exceed 5 min.