Question

    Train P travelling at 42 km/hr crosses another train Q,

    having three fourth of its length and travelling in opposite direction at 30 km/hr in 21 seconds. Train P passed a railway platform in 36 seconds. Find the length of platform.
    A 180 m Correct Answer Incorrect Answer
    B 350 m Correct Answer Incorrect Answer
    C 130 m Correct Answer Incorrect Answer
    D 380 m Correct Answer Incorrect Answer
    E 200 m Correct Answer Incorrect Answer

    Solution

    Let the length of the first train is x metre Length of second train = 3x/4 Therefore, (42 + 30) x 5/18 = {x + (3x/4)}/21 ⇒ 72 x 5/18 = (7x/4)/21 ⇒ x = 240 m Therefore, let the length of the platform be y metre ⇒ 42 x 5/18 = (240 + y)/36 ⇒ 420 = 240 + y ⇒ y = 420 – 240 = 180 m

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