Two trains, 145 m and 155 m in length, run on parallel tracks. One train runs at the speed of 32 km/h and the other at 40 km/h. When both trains run in opposite direction, then the time required for them to cross each other completely from the moment they meet is:

Correct option is A

Given:

Lengths of trains: 145 m and 155 m

Speeds: 32 km/h and 40 km/h

Direction: Opposite

Need to find time to cross each other completely.

Formula Used:

Time $$= \frac{\text{Sum of lengths}}{\text{Relative speed}}$$​

Solution:

Total length = 145 + 155 = 300 m

Relative speed = 32 + 40 = 72 km/h

Now,

Time =$$\frac{300}{72 \times \frac{5}{18} } = \frac{300}{20 \text{ m/s}} = 15 \text{ seconds}$$​