A train 125 m long passes a man, running at 4 km/hr in the same direction in which the train is going, in 10 seconds. The speed of the train is:  Choose the correct option:
A) 49 kmph B) 50 kmph C) 51 kmph D) 52 kmph E) 54 kmph
Explanation:   Speed of the train relative to man   = (125/10) m/sec = (25/2) m/sec.   [(25/2) x (18/5)] km/hr = 45 km/hr.   Let the speed of the train be 'x' km/hr.   Then, relative speed = (x - 4) km/hr.   x - 4 = 45 =&gt; x = 49 km/hr.   49 kmphNSWER IS 49 kmph
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A train 125 m long passes a man, running at 4 km/hr in the same direction in which the train is going, in 10 seconds. The speed of the train is: