Question

A 150 m long train takes 25 seconds to cross a girl who is going in the same direction with a speed of 5 km/h. After crossing that girl, the train can reach the next station in 30 min. How long did the girl take to reach that station after being crossed by the train?
1. 1.9 hours
2. 1.2 hours
3. 1.7 hours
4. 9.8 hours
5. 1.8 hours

Answer 1

Correct Answer - Option 3 : 1.7 hours

Calculations:

Speed of the girl = 5 km/h

⇒ 5 × 5/18 m/s

⇒ 25/18 m/s

Let speed of train be x m/s

∴ Relative speed of train = (x – 25/18) m/s

As, train takes 45 s to cross the girl

⇒ 45 = 150/(x – 25/18)

⇒ x – 25/18 = 150/45

⇒ x = 10/3 + 25/18

⇒ x = 85/18 m/s

Now, distance covered by the train in 30 mins

⇒ 85/18 × 30 × 60

⇒ 8500 m

⇒ 8.5 km

Thus, time taken by the girl to cover this distance of 8.5 km

⇒ 8.5/5

⇒ 1.7 hours

The time taken by the girl is 1.7 hours.