17. Unique Tyre Company decided to hire a new mechanic to handle all tyre changes for customers ordering a new set of tyres. Two mechanics applied for the job. One mechanic has limited experience, can be hired for Rs 14 per hour, and can service an average of three customers per hour. The other mechanic has several years of experience, can service an average of four customers per hour, but needs to be paid Rs 20 per hour. Assume that the customers arrive at the company garage at the rate of two customers per hour.

Calculate the following characteristics of the queuing system using each mechanic, assuming Poisson arrivals and exponential service times:

(i) Expected length of queue,

(ii) Expected length of system,

(iii) Expected waiting time in queue, and

(iv) Expected waiting time in the system.

If the company assigns a customer waiting time cost of Rs 30 per hour, which mechanic provides the lower operating cost? (M Com, Delhi, 2009)