# How Much Time Will The Train Take to Travel 108 km?

A train takes 20 second to cross a person a person who is travelling at a speed of 9 km/hr in the same direction. If the length of the train is 150 meter, then how much time will the train take to travel 108 km?

- 4 hours
- 10.8 hours
- 3 hours
- 5 hours

**Answer: (3) 3 hours**

**Explanation:-**

Let the speed of a train = X km/h

Speed of a person = 9 km/h

Speed in m/sec = 9 x 5/18

= 5/2 m/sec

The length of the train = 150 m

According to the question,

150 /(X – 5/2) = 20

150 x 2/(2 X – 5) = 20

300 = 20 (2 X – 5)

300 = 40 X – 100

40 X = 300 + 100

40 X = 400

X = 400/40

X = 10 m/sec

Speed in km/h = 10 x 18/5

= 18 x 2 = 36 km/h

The speed of the train = 36 km/h

Time taken by train to covered the distance 108 km = 108/36

= 3 h.

Hence,the answer is (3) 3 hours.