Question

Two trains are running in opposite directions with the same speed. If the length of each train is 120 metres and they cross each other in 12 seconds, then the speed of each train (in kmph) is:

• A. 30
• B. 18
• C. 36
• D. 72
• E. 80

Answer 1

The correct option is C

36

Let the speed of each train be `x' m/sec

Then, relative speed of the two trains = 2x m/sec.

So, 2x = $\frac{\left(120+120\right)}{12}\iff 2x=20\iff x=10$

$\therefore$Speed of each train = 10 m/sec =$\left(10\times \frac{18}{5}\right)$ kmph = 36 kmph