Question: A worker is currently responsible for tending two machines (n = 2) in a machine cluster. The service time per machine Ts = 0.35 min. and the time to walk between machines Tr = 0.15 min. The machine automatic cycle time Tm - 1.90 min. If the worker's hourly rate = $12/hr and the hourly rate for each machine = $18/hr, determine:
(a) the current hourly rate for the cluster and
(b) the current cast per unit of product. given that two units are produced by each machine during each machine cycle.
(c) What is the percentage idle time of the worker?
(d) What is the optimum number of machines that should be used in the machine cluster, if minimum cost per unit of product is the decision criterion?