Question

A train 250 m long meets a man going in opposite direction at 5km/h and passes him in 10 seconds. What is the speed of the train in km/h?
1. 90 km/h
2. 85 km/h
3. 80 km/h
4. 95 km/h

Answer 1

Correct Answer - Option 2 : 85 km/h

GIVEN:
Train's length = 250 m

Man's speed = 5 km/h

Time taken to pass = 10 sec

CONCEPT:

• Distance traveled in crossing a man is equal to the length of the train.
• When two objects are moving in opposite directions relative speed is the sum of their individual speeds.

FORMULA USED:

Speed = Distance/Time

CALCULATION:
Let speed of train be x km/h

∴ Relative speed = (x + 5) km/h

Distance = 250 m = 1/4 km

Time = 10 sec = 10/3600 hr

∴ (x + 5) = (1/4)/(10/3600)

(x + 5) = 3600/40 = 90 km/h

X = 85 km/h

∴ Speed of train is 85 km/h.