20. A mechanic is to be recruited to repair scooters that breakdown at an average rate of 6 per hour. The breakdowns follow a Poisson distribution. Non-productive time of a scooter costs Rs 40 per hour.

Mechanics A and B have been interviewed for the purpose. Mechanic A charges Rs 20 per hour, and services scooters at the rate of 8 per hour. Mechanic B charges Rs 28 per hour, and services 12 scooters per hour, on an average. Which one of the two should be recruited and why? Assume an 8 hours of work each day. (M Com, Delhi, 2007)