There are two machines that break down with a probability of 0.2 (each) per day. This is a binomial probability of 0, 1 or 2 failures per day with probabilities of .64, .32 and .04 respectively. You can hire one or two repairmen at a cost of $50 per man per day. Machine downtime costs you $80 per hour if one machine is down but $120 per hour if both machines are down. One man can fix a machine in four hours and two men working together can fix a machine in three hours.
The total maintenance cost (including downtime cost) in the case of two repairmen on duty is:
a. $96
b. $134
c. $150
d. $196
e. None of these.