(A) 50 km/hr
(B) 60 km/hr
(C) 130 km/hr
(D) 140 km/hr
Correct Option is: A
Length of the train = 200 m
Man walking speed = 10 km/hr
Let the speed of the train be ‘x’ km/hr
Speed of the train relative to man = (x +10) km/hr
Convert km/hr into m/s
(x +10)km/hr = (x + 10) * 5 / 18 m/s
Speed = distance / time
200 / (x + 10)* 5 / 18 = 12
18 * 200 / 5(x + 10) = 12
3600 = 60(x +10)
3600 = 60x +600
60x = 3000
X = 50
So speed of the train is 50 km/hr