(Solved): 15.- At a Manufacturing Company, repair technicians have been assigned the responsibility of mainta ...

15.- At a Manufacturing Company, repair technicians have been assigned the responsibility of maintaining four machines that perform their work after a set-up. The set-up time of each machine has an exponential distribution, with a mean of thirty minutes. After each set-up, the technician presses a button and the machine works alone until its function is finished. At this time, the machine needs another set-up to start over. The machines work alone during periods of time that follow an exponential distribution with an average mean of one hour. The company will pay 12 euros/hour to each operator, and the cost for a stopped machine is estimated at 33 euros/hour. Determine if 1, 2, 3, or 4 technicians are needed in order to minimize the total expected cost.