Two trains, 250 metres and 150 metres long respectively, are running on parallel lines. if they are running in the same directions, the faster train crosses the slower train in 40 seconds. if they are moving in the opposite direction they pass each other in eight seconds. what is the speed of the slower train?

Question: Two trains, 250 metres and 150 metres long respectively, are running on parallel lines. if they are running in the same directions, the faster train crosses the slower train in 40 seconds. if they are moving in the opposite direction they pass each other in eight seconds. what is the speed of the slower train?

Let the speed of the slower train be v.

The speed of the faster train is v + x, where x is the relative speed of the two trains when they are moving in the same direction.

When the trains are moving in the same direction, the faster train travels a distance of 250 + 150 = 400 meters in 40 seconds.

The relative speed of the two trains is:

(400 meters) / (40 seconds) = 10 meters per second.

Therefore, x = 10 meters per second.

When the trains are moving in the opposite direction, the faster train travels a distance of 250 + 150 = 400 meters in 8 seconds.

The relative speed of the two trains is:

(400 meters) / (8 seconds) = 50 meters per second.

Therefore, v + x = 50 meters per second.

Substituting x = 10 meters per second, we get v = 40 meters per second.

The speed of the slower train is 40 meters per second.

Converting this to kilometers per hour, the speed of the slower train is 40 * 3600 / 1000 = 144 kilometers per hour.

So the answer is 144.