Aptitude Hack#18(13-3-19)

Question:
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:

A. 45 km/hr
B. 50 km/hr
C. 54 km/hr
D. 55 km/hr

Answer: Option B

Explanation:

The speed of the train relative to man =125/10 m/sec

   =25/2 m/sec.
   = 25/2 x18/5 km/hr
   = 45 km/hr.

Let the speed of the train be x km/hr. Then, relative speed = (x - 5) km/hr.(Same Direction)

 x - 5 = 45  
 x = 50 km/hr.