A 150-meter-long Train A crosses a pole in 10 seconds. The speed of Train B is 20% more than the speed of Train A, and the ratio of the length of Train A to Train B is 5 : 6. If Train B crosses a platform in 20 seconds, find the length of the platform.

ATQ, Train A crosses a pole in 10 seconds. So, speed of Train A = Length / Time Speed of Train A = 150/10 = 15 m/s The speed of Train B is 20% more than Train A. So, speed of Train B = 15 × 120/100 = 18 m/s The ratio of the length of Train A to Train B is 5 : 6. Length of Train A = 150 meters = 5 parts. So, 1 part = 150/5 = 30 meters. Length of Train B = 6 parts = 6 × 30 = 180 meters. Train B crosses a platform in 20 seconds. Distance covered by Train B in 20 seconds = Speed × Time Distance covered = 18 × 20 = 360 meters. When a train crosses a platform, distance covered = length of train + length of platform. So, Length of Train B + Length of platform = 360 180 + Length of platform = 360 Length of platform = 360 − 180 = 180 meters.