QUESTION 6. [10 points] A small call center normally has 5 employees answering calls while open. On average, 5 calls arrive every 4 minutes with a CVa = 1. Under normal operating conditions each employee on average handles each call in 3.5 minutes with a standard deviation of 3. Today, however, one employee has the flu, and they need to operate with 4 employees during this time. The manager is nervous that they may be supply constrained and so she directs her employees to hurry their processing of calls today. What is the maximum average processing time for each call that they need to achieve today so that they have a stable queue? (Note: there will be supply constrained if their processing time is higher than this target and there will be demand constrained if it is lower than this target. Choose the closest answer. Assume CVa and CVp don't change even after the potential change in processing times)