A train 125 m long passes a man, running at 7 km/hr in the same direction in which the train is going, in 10 seconds. The speed of the train is: Pick
A) 35 km/hr B) 50 km/hr C) 45 km/hr D) 52 km/hr E) 87 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 - 7) km/hr. x - 7 = 45 ==&gt; x = 52 km/hr.   Answer: 52 km/hr
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A train 125 m long passes a man, running at 7 km/hr in the same direction in which the train is going, in 10 seconds. The speed of the train is: