The supervisor at the Precision Machine Shop wants to determine the staffing policy that minimizes total operating costs. The average arrival rate at the tool​ crib, where tools are dispensed to the​ workers, is machinists per hour. Each​ machinist's pay is ​$ per hour. The supervisor can staff the crib either with a junior attendant who is paid ​$ per hour and can process arrivals per hour or with a senior attendant who is paid ​$ per hour and can process arrivals per hour. Which attendant should be​ selected? The ▼ senior attendant junior attendant should be​ selected, with a total estimated hourly cost of ​$ nothing. ​(Enter your response rounded to two decimal places​.)