Suzy's pretzel shop employs a single customer service employee (Suzy), who takes orders for pretzel, fills them, and takes payment. She services at most one customer at a time. The time required to service a customer is random, and is exponentially distributed with a mean of 25 seconds. Customers arrive at an average rate of 120 customers per hour with exponentially distributed inter-arrival times. Arriving customers never balk or renege. a) What fraction of time is Suzy busy? b) What is the standard deviation of the service time distribution? c) What is the average wait time for a customer in seconds? d) Suzy's chief competitor is another pretzel shop, Roxanne's. Roxanne works at the same speed as Suzy but has less variability in her service times. Assuming inter-arrival times at Roxanne's are exponentially distributed with an average rate of 120 customers per hours, which shop would you expect to have shorter wait times? a. Suzy's b. Roxanne's C. Neither. The wait times will be approximately equal. d. We do not have enough information to answer the question.