Question 16 (6 points) An average of 40 customers per hour arrives at a bank branch office (Poisson arrival) and wait in a single line to be served by the first available teller. The average time for each teller to service a customer is 4 minutes (exponentially distributed). Each teller earns $160/ day and the bank branch office assesses a waiting cost of $50/ day that a customer waits in the system. How many tellers should be on duty in this bank branch office to minimize the total cost of this waiting line system? Question 17 (3 points) Refer to the information in Q16. For the optimal waiting line system decided in Q16, find the probability that at least one teller is busy. 0.057 0.943 0.043 0.891 Question 18 (3 points) Refer to the information in Q16. For the optimal waiting line system decided in Q16, find the average time spent in the system per customer. 0.0869 hours 0.0569 hours 0.0879 hours 0.0861 hours Question 19 (3 points) Refer to the information in Q16. For the optimal waiting line system decided in Q16, find the average time spent in the line per customer. 0.0413 hours 0.0203 hours 0.0243 hours 0.1205 hours