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 km/hr) is:

A 10

B 8

C 36

D 72

Correct Answer: Option C

Since the trains are going in opposite direction, The relative speed will be sum of both.

Again, each train has to cross 120 + 120 metres to cross the other train.

So, in 12 seconds they go 240 meters

1 second they go 20 meter.

That is the relative speed.

Speed of each train will be 20/2 = 10m/sec = 10 * 3600/ 1000 kmph =36kmpr