Mr. W operates a small restaurant at Berkeley. Customers can only take out the foods through walk-in service. Once a customer arrives, an order will be placed immediately and a cook of the restaurant will process orders in a first come first serve pattern. After an order is finished by a cook, the customer will pick up the food and leave immediately. During the time the food is prepared, a customer waits in the restaurant. There is infinite size of waiting area. For simplicity, we assume this restaurant opens 24 hours every day and customers arrive to the restaurant according to a Poisson process with constant rate 20 per hour. The cooking time for each order is exponentially distributed with rate 25 per hour. Each cook in the restaurant can only process one order at one time. Each cook works independently. The time it takes to place an order is considered to be negligible (e.g., through mobile apps or kiosks) and is not counted in the model. Consider a continuous time stochastic process {X(t) : t 0} where X(t) is the number of customers in the restaurant at time t. a.) Suppose that there is only one cook in