6. Semi-finished components arrive at one work station on an assembly machine in a random fashion at the rate of 10 units per hour. A machine is required to carry out the operation at this work station. Three models of machines A, B and C are under evaluation for which the costs and operating data are shown below. The cost of the machines will be fully written-off over three years’ of usage. The assembly line works an effective 6 hours per day on an average 250 days a year.

Whenever a component that has arrived is waiting to be processed at this work station there is an idle time cost at the rate of Rs. 24 per hour.

Using the concepts of queuing theory and considering all cost factors recommend which machine should be installed as the most economical?