A worker is currently responsible for tending two machines in a certain production cell. The service time per machine is 0.35 min and the time to walk between machines is 0.15 min. The machine automatic cycle time is 1.90 min. If the worker's hourly rate is $12/hr and the hourly rate for each machine is $18/hr, determine
(a) the current hourly rate for the cell, and
(b) the current cost per unit of product, given that two units are produced by each machine during each machine cycle.
(c) What is the percentage of idle time of the worker? (d) What is the optimum number of machines that should be used in the cell, if minimum cost per unit of product is the decision criterion?