A call center normally has 5 employees answering calls while open.on average five calls arrive every four minutes. under normal operation conditions each employee on average handles each call in 3.5 minutes. but today one employee has the flu and they need to operate with four employees.the manager thinks there might be a supply constraint, so she directs her employees to hurry the calls for the day. what is the maximum average processing time for each call that they need to achieve today so that they can have a stable queue?