Multiple choice

A train moves at the speed of 108 km/hr, passes a platform and a bridge in 15 sec and 18 sec respectively. If the length of platform is 50% of length of bridge, then find the length of train.

  1. 370 m

  2. 360 m

  3. 340 m

  4. 320 m

  5. 350 m
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Speed = 108 km/h = 30 m/s. Let train length be L and bridge length be B. Platform length = 0.5B. L + 0.5B = 30 * 15 = 450. L + B = 30 * 18 = 540. Subtracting equations: 0.5B = 90, so B = 180. Then L + 90 = 450, L = 360.

AI explanation

Let the length of the bridge be B, so the length of the platform is 0.5B. The speed of the train is 108 km/hr, which converts to 108 multiplied by 5/18, giving 30 m/s. The total distance covered to pass the platform is 30 multiplied by 15, equaling 450 meters. The total distance covered to pass the bridge is 30 multiplied by 18, equaling 540 meters. Let L be the length of the train. We then have L + 0.5B = 450 and L + B = 540. Subtracting the first equation from the second gives 0.5B = 90, so B = 180 meters. Substituting B back into the first equation gives L + 90 = 450, meaning the length of the train L is 360 meters.

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