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: Select:	A) 38 km/hr	B) 40 km/hr	C) 44 km/hr	D) 50 km/hr	E) None
Sol.   Speed of the train relative to man = [125/10] m/sec = [25/2] m/sec.   = [25/2 * 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.   Answer 50 km/hr
<result>D</result>
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: