You are working as a methods engineer at Sorona Company and your manager asked you to identify the number of machines to be assigned for the drilling operator. The operator service time for the drilling machine is 3.1 minutes and the drilling machine's cycle run time is 6.5 minutes. When multiple machines are assigned to one operator, it takes 0.3 minutes for the operator to walk from one drilling machine to another. The drilling operator cost is $20/hr and the machine cost is $25/hr. Assume that each drilling machine produces 3 items per cycle. Given the information determine how many drilling machines should be assigned to the operator by comparing the unit costs for the items produced