1)

A train 125 m long passes a man, running at 5 kmph 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

E) 56 km/hr

Answer:

Option B

Explanation:

Speed of the train relative to man $=\left(\frac{125}{10}\right)$ m/sec $=\left(\frac{25}{2}\right)$ m/sec.

$=\left(\frac{25}{2}\times\frac{18}{5}\right)$ km/hr $=45$ km/hr.

Let the speed of the train be $x$ kmph. Then, relative speed $=(x-5)$ kmph.

$\therefore$ $x-5=45$ or $x=50$ kmph.