The women's department at Hector's Department Store has a single checkout register. Customers arrive at the register at the rate of 12 per hour. It takes the clerk, on average, 4 minutes to check out a customer. a. The average number of customers waiting to be checked out is (Enter your response rounded to two decimal places.) b. On average, a customer will have to wait minutes before the clerk starts serving him or her. (Enter your response rounded to one decimal place.) c. Hector's Department Store has decided to add a second checkout register. This second register works at the same average speed as the first. Customer arrivals are the same as before. The average number of customers waiting to be checked out now is customers. (Enter your response rounded to tvo decimal places.) d. On average, a customer will have to wait now minutes before the clerk starts serving him or her. (Enter your response rounded to one decimal place.)