Question

A man walking in a railway tunnel for repairing starts running in the opposite direction after getting a signal of a train having a speed of 162 km/hr coming towards him. What should be the minimum speed so that he may reach at exit point before the train which is 400 m away from him and 9 km away from the train?
1. more than 8 m/sec
2. more than 4 m/sec
3. more than 1 m/sec
4. more than 2 m/sec

Answer 1

Correct Answer - Option 4 : more than 2 m/sec

Given,

Speed of train = 162 km/hr

Distance between train and exit point = 9 km

Formula used, Time = Distance/Speed

Calculation 

Speed of train = 162 km/hr

= 162 × (5/18) m/sec = 45 m/sec

Distance between train and exit point = 9 km

= 9000 metres

Time is taken by train to reach exit point = Distance between train and exit point/Speed

= 9000/45 = 200 seconds

To reach the exit point, man should take less than 200 seconds

Speed of man = 400/200 = 2 m/sec

∴ Speed of man should be more than 2 m/sec