If a train 130 m long takes seconds to cross a man who is walking at 12 km/h in the same direction in which the train is going, then the speed of the train (in km/h) is:
Show answer & explanation
Correct answer: A
Explanation
The correct answer is option 1 i.e. 84.
Length of the train = 130 m
Speed of the man = 12 km/h
Time = 6= 6.5 seconds
Relative speed in same direction = (Speed of train - Speed of man)
Time = Length of the train/(Speed of train - Speed of man)
Let's assume the speed of the train = x km/h
⇒ 6.5 = 130/(x - 12)
⇒ x - 12 = 20 × = 72
⇒ x = 84 km/h