New Enroll in RBI Grade B New Batch - Starts on May 21

    Question

    Train A running at speed of 81 km/hr crosses a platform

    having twice the length of train in 12 sec. Train B whose length is 360m crosses same platform in 18 sec, then find the speed of train B ?
    A 72 km/hr Correct Answer Incorrect Answer
    B 108 km/hr Correct Answer Incorrect Answer
    C 142 km/hr Correct Answer Incorrect Answer
    D 144 km/hr Correct Answer Incorrect Answer
    E 54 km/hr Correct Answer Incorrect Answer

    Solution

    Let length of train A = x Length of platform = 2x Speed = distance/time ⇒ 81 x 5/18 = (x + 2x)/12 ⇒ x = 90 m = length of train A Length of platform = 90 x 2 = 180m For train B, Speed = distance/time ⇒ (180 + 360)/18 x (18/5) ⇒ 108 km/hr 

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