Question

The ratio of the speed of the train and a man is 12 ∶ 1. The length of the train is 360 m and crosses a man standing on platform in 18 sec. In how many time, the man will cross 240 m long platform.
1. 120 sec
2. 144 sec
3. 2 min
4. 3 min

Answer 1

Correct Answer - Option 2 : 144 sec

Given:

Length of train = 360 m

Time taken to cross a man = 18 sec

Ratio of speed of train to man = 12 ∶ 1

Formula used:

Time = Distance/Speed

If any train crosses a man/pole or any other vertical object, distance travelled by train is equal to length of the train

Calculations:

Speed of train = 360/18 = 20 m/sec

Ratio of speed is 12 ∶ 1

Let speed of train be 12x and speed of man be x

∵ 12x = 20 m/sec

∴ x = 20/12 = 5/3 m/sec

Speed of man = (5/3) m/sec

Time taken to cross the platform = (240/5) × 3 = 144 sec.

∴ Time taken to cross the platform is 144 sec.