A train running at a speed of 81 km/h passes 375 m long tunnel in 40 seconds. What  is the length of the train (in m ) ?

525

Let the length of the train be ‘x’ m

Length of platform = (x + 375) m

Speed of train = 81 km/hr. = 81 × 5/18 = 22.5 m/sec.

∵ Time taken to cross the platform = (Sum of lengths of train & platform)/speed of train

⇒ 40 = (x + 375)/22.5

⇒ 900 = x + 375

⇒ x = 525m