A train 125 m long passes a man, running at 5 km/hr in the same direction in which the train is going, in 10 seconds. The speed of the train is? Choose the correct choice from the following.
A) 65 km/hr
B) 50 km/hr
C) 21 km/hr
D) 25 km/hr
E) 76 km/hr
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 km/hr. Then, relative speed   = (x - 5) km/hr. x - 5 = 45 ==&gt; x   = 50 km/hr.   Answer: 50 km/hr
<result>B</result>
A train 125 m long passes a man, running at 5 km/hr in the same direction in which the train is going, in 10 seconds. The speed of the train is?