Question

A train of 120 m long is running with a speed of 65 kmph. In what time will it pass a man who is running at a speed of 5 kmph in the same direction in which the train is running.
1. 5.8 sec
2. 6.6 sec
3. 8.4 sec
4. 7.2 sec

Answer 1

Correct Answer - Option 4 : 7.2 sec

Given 

Length of a train = 120 m

Speed of the train = 65 km/hr

Speed of the man in the same direction = 5 km/hr

Formula used 

Relative speed in same direction = speed of the train - speed of the man

Time = Distance/Speed 

1 km/hr = 5/18 m/sec

Calculation

Relative speed is (60 - 5) = 60 km/hr. 

 At a speed of 60 km/hr into m/s = 60 × 5/18 = 50/3 m/sec

Time = 120/(50/3) = 36/5 = 7.2 sec.

∴ Time taken by the train to cross the man is 7.2 sec.