arithmetic - a train 125 m long passes a man running at 5 kmph in the same direction in which the train is going in 10 seconds the speed of the train is - skillgun

Speed of the train relative to man =
125/10m/sec = 25/2 m/sec. =
25/2 x 18/5 km/hr = 45 km/hr.
Let the speed of the train be x kmph. Then, relative speed = (x – 5) kmph.
x - 5 = 45 or x = 50 kmph.