A 230 meters long train running at the speed of 80 km/hr crosses another train running in opposite direction at the speed of 120 km/hr in 9 seconds. What is the length of the other train?

Question: A 230 meters long train running at the speed of 80 km/hr crosses another train running in opposite direction at the speed of 120 km/hr in 9 seconds. What is the length of the other train?

Solution:
Relative speed = (80 + 120) km/hr
= 200 km/hr
= (200 × 1000)/3600 m/s
= 500/9 m/s

Let,
The length of the other train be x meters.

Now,
(x + 230)/9 = 500/9
⇒ x + 230 = 500
⇒ x = 500 - 230
∴ x = 270

∴ The length of the other train is 270 meters