SSC Sample Paper Mock Test-12 SSC CGL Tear-II Paper-1

Two trains are running in opposite direction with the same speed. If the length of each train is 120 m and they cross each other in 12 s, the speed of each train (in km/h) is

A) 72

B) 10

C) 36

D) 18

Correct Answer: C

Solution :

Let the speed of each train be x km/h.

Their relative speed \[=x+x=2x\] km/h

Time taken \[\text{=}\frac{\text{Total}\,\,\text{length}\,\,\text{of}\,\,\text{trains}}{\text{Relative}\,\,\text{speed}}\]

\[\Rightarrow \]\[\frac{12}{60\times 60}=\frac{240\times \frac{1}{1000}}{2x}\]\[\Rightarrow \]\[\frac{1}{300}=\frac{120}{1000x}\]

\[\Rightarrow \] \[x=\frac{300\times 120}{1000}=36\]

\[\therefore \]The required speed = 36 km/h