Two trains travelling in opposite directions cross each other in 25 seconds. If the length of both the trains is 250 m each and the speed of one of them is 45 km/hr, what be the speed of the other train?

Correct option is C

Given:

Length of each train = 250 m

Time taken to cross each other = 25 seconds

Concept Used:

Relative Speed =$$\frac{\text{Total Distance}}{\text{Time}}$$​​​

Solution:
Let the speed of second train be x m/sec
Speed of one train in metre per sec = 45$$\times \frac{5}{18}= \frac{25}{2}m/sec$$

Total distance covered = Length of Train 1 + Length of Train 2 = 250 + 250 = 500 m

Relative Speed =$$\frac{500}{25} = 20 m/s$$​ 

x+ $$\frac{25}{2}m/sec$$ = 20 m/sec

x = $$\frac{15}{2} m/sec$$
In km/hr = $$\frac{15}{2} \times \frac{18}{5} = 27 km/hr$$​​