An 800-metre-long train can pass a stationary pole completely in 72 seconds. A 1200-metre-long train can also pass a stationary pole completely in 72 seconds. If both the trains are running in the same direction, then the faster train, coming from behind the slower train, can cross the slower train in how much time?

360 seconds

Speed of train 1 = \(\frac{Distance}{Time}\)

= \(\frac{800}{72}\) = \(\frac{100}{9}\) m/sec

Speed of train 2 ( faster train) = \(\frac{1200}{72}\) = \(\frac{50}{3}\) m/sec

Relative speed when they moves in same direction = \(\frac{50}{3}\)  - \(\frac{100}{9}\) = \(\frac{50}{9}\) m/sec

Time taken by faster train to cross slower train = \(\frac{2000 × 9 }{50}\) 

= 360 seconds