Given: Speed = 90 km/h Time = 8 seconds. Formula used: Distance = Speed × Time Calculation: According to the questions: Speed = 90 km/h ⇒ 90 × (5/18) m/sec. ⇒ 25 m/sec Now, Distance = Speed × Time ⇒ D = 25 × 8 ⇒ 200 meter. When the train to cross the platform of length 250 meter, Total distance = (200 + 250) meter ⇒ 450 meter. Time = distance/Speed ⇒ 450/25 ⇒18 seconds. ∴ The time taken by the train to cross the platform of length 250 meters is 18 seconds.