The Chattanooga Furniture store gets an average of 50 customers per shift. Marilyn? Helms, the? manager, wants to calculate whether she should hire 1 ?, 2 ?, 3 ?, or 4 salespeople. She has determined that average waiting times will be 7 minutes with one? salesperson, 4 minutes with two? salespeople, 3 minutes with three? salespeople, and 2 minutes with four salespeople. She has estimated the cost per minute that customers wait at ?$1 . The cost per salesperson per shift? (including fringe? benefits) is ?$70 .