A small branch bank has two tellers, one for deposits and onefor withdrawals. Customers arrive at each teller’s window with anaverage rate of 18 customers per hour. (The total customer arrivalrate is 36 per hour.) The interarrival times are exponential. Theservice time of each teller is exponential with a mean of 3minutes. The bank manager is considering changing the setup toallow each teller to handle both withdrawals and deposits to avoidthe situations that arise from time to time when the queue issizable in front of one teller while the other is idle. However,since the tellers would have to handle both deposits andwithdrawals, their efficiency would decrease to a mean service timeof 3.2 minutes. Compare the present system with theproposed system with respect to the total average numberof customers in the banks and the average time a customer wouldhave to spend in the bank.
