4. A restaurant has 4 chefs, 2 waiters. These four chefs work in parallel and the effective working times are 16 minutes per dish with a standard deviation of 5 minutes. Once the dish is ready, one of the two waiters takes 1 minute (effectively, with a standard deviation of 1 minute) to place the dish to the table. Each waiter can only handle one dish at a time and needs to take a rest for exactly 8 minutes after every hour, indicating there is no variation of the resting times. Customers place orders at an average rate of 1 dish every 5 minutes. Assume Ca= 2. (24 points) a. Compute the average waiting time for the chefs. b. Calculate the average time to finish one dish by considering the waiting time. c. Compute the average time a dish has to wait for the waiter once it has been finished by the chef. d. What is the total processing time of a dish to be placed on the table? Which one is the bottleneck, a chef, or a waiter? Justify your choice. e