Question

A train passes a station that is 270 m long in 90 sec. at a speed of 108 km / hr. The time taken by the train to pass a bird feeder is:
1. 45 seconds
2. 60 seconds
3. 81 seconds
4. 55 seconds

Answer 1

Correct Answer - Option 3 : 81 seconds

Given:

Length of the station = 270 m

Time taken on crossing the station = 90 sec

Speed = 108 km / h

Concept:

Crossing a bird feeder = crossing its own length

Crossing a station = Crossing the combined length of train and station.

Calculations:

Speed of train = 108 km / h = 108 × 5 / 18

⇒ 30 m / s

Let the length of the train be x metres.

Then, (x + 270) / 30 = 90

⇒ x + 270 = 90 × 30

⇒ x + 270 = 2700

⇒ x = 2430

So, time taken by the train to cross the bird feeder

⇒ 2430 / 30

⇒ 81 s

The time taken by the train to cross the bird feeder is 81 seconds.