Question

The ratio of the speeds of a train and man is 9 ∶ 2. The train having a length of 450 metres crosses a post in 50 seconds. Calculate the time the train will take to cross the man while going in the same direction. (approx.)

1. 34 seconds
2. 64 seconds
3. 51 seconds
4. 33 seconds
5. 66 seconds

Answer 1

Correct Answer - Option 2 : 64 seconds

Given:

The length of the train is 450 m

Time taken to cross-post is 50 seconds

The ratio of speed of train and man is 9 ∶ 2

Concept:

Distance covered in crossing a post or a man is equal to the length of the train.

Relative speed while going in the same direction is the difference of the speeds.

Formula:

Speed = distance/time

Time = distance/speed

Calculation:

Speed of train = 450/50 = 9 m/s

Speed of man = 90 × (2/9) = 2 m/s

Relative speed = 9 – 2 = 7 m/s

Time to cross the man = 450/7 = 64.28 seconds (approx.)

∴ Time taken by the train to cross the man is 64 seconds