A train crosses a platform at 54 km/hr in 20 seconds. Another train is 150 m shorter than the former and is running at 36 km/hr. Find the time the second train will take to cross the same platform.
Explanation:
Speed of the first train is 54 × 5/18 = 15 m/s.
(Length of the platform + length of the train) is =20 × 15
= 300 m. If the second train is 150 m shorter,
then the length of the platform + length of the second train is 300 – 150 = 150 m.
That train is running at 36 km/hr = 36 × 5/18 = 10 m/s.
So it will take 150 / 10 = 15 seconds to cross the platform.
Hence, option 3 is the correct answer.
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By: Amit Kumar