Charlie's Barbershop is a popular haircutting and styling salon near the campus of Western Carolina University. Four barbers work full time and spend an average of 15 minutes on each customer. Customers arrive all day long, at an average rate of 10 per hour. When they enter, they take a number to wait for the first available barber. a) What type of system is this? b) What is the average number of customers in the barbershop? (Enter two decimal places) c) What is the average time that a customer spends waiting (in minutes) to be called to a chair? (Enter two decimal places) d) What is the average number of customers waiting to be served? (Enter two decimal places) e) What percent of time are the barbers busy cutting and styling? (Enter three decimal places) f) Charlie want's his employees to be busy cutting and styling at least 80% of the time, what is the fewest number employees that should be on duty to meet this requirement