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UPSC Civil Service Exam Questions - Engineering

Q1:

A bulldozer operates on a 30 m stretch and moves at 2.4 kmph when pushing the earth, and returns empty at 6 kmph. The time lost in loading and shifting gears per trip is 18 seconds. Its operating factor is nearly 50 min/hour. What is the number of trips made per hour ?

A 31

B 33

C 35

D 37

ANS:D - 37

2.4 km/h = 2.4*5/18 m/s = 0.66666 m/s.
6 km/h= 1.66666 m/s.

The time taking one trip = (30/0.666)+(30/1.6666)+18=45+18+18 = 81.
One trip time 81 second.
One hour trip 3600/81 = 44.4444,
But operation efficiency = 44.4444 * (50/60).
= 37.