Two trains of equal length are running on parallel lines in the same direction at speeds of 49 km/h and 31 km/h. The faster train passes the slower train in 42 seconds. The length of each train is:

Correct option is C

Given:

Speeds of the trains: 49 km/h and 31 km/h

Time taken to pass = 42 seconds

Trains are of equal length

Moving in same direction

Formula Used:​

Distance = Relative Speed × Time

​Solution:

Relative Speed = (49 − 31) = 18 km/h

in m/s, $$= \frac{18 \times5}{18} =5 \, \text{m/s}$$​​

Distance = $$5\times 42 = 210 \, \text{m}$$​​

Since both trains are equal in length:

Each Train’s Length = $$\frac{210}{2} = 105 \, \text{m}$$