A train passes two persons who are walking in the opposite direction of the train at the rates of 4 m/s and 10 m/s in 10 seconds and 8 seconds respectively. What is the speed of the train?

Correct option is B

Given:

- Speed of the first person = 4 m/s
- Speed of the second person = 10 m/s
- Time taken to pass the first person = 10 seconds
- Time taken to pass the second person = 8 seconds
- The persons are moving in the opposite direction to the train.

Formula Used:

Relative Speed = Speed of Train + Speed of Person
Distance covered by the train = Relative Speed × Time
Since the distance covered is the same for both persons, we can equate the two equations.

Solution:

Let the speed of the train be 'x' m/s.
For the first person:
Distance = (x + 4) × 10
For the second person:
Distance = (x + 10) × 8
Equating the two distances:
(x + 4) × 10 = (x + 10) × 8
10x + 40 = 8x + 80
=> 2x = 40
=> x = 20 m/s
Thus, the speed of the train is 20 m/s.