A train 200 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 answer.
A) 45 km/hr
B) 50 km/hr
C) 77 km/hr
D) 55 km/hr
E) 56 km/hr
Speed of the train relative to man = (200/10) m/sec = 20 m/sec. [20 * (18/5)] km/hr = 72 km/hr. Let the speed of the train be x km/hr. Then, relative speed = (x - 5) km/hr. x - 5 = 72==&gt; x = 77 km/hr.   ANSWER: 77 km/hr
<result>C</result>
A train 200 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: