Multiple choice

Train A running with the speed of 36 km/hr crosses a pole in 20 seconds. Another train B whose length is 100 metre more than length of train A is running with the speed of 18 km/hr. Find the time taken by train B to cross a platform of length 500 metre.

  1. 200 seconds

  2. 160 seconds

  3. 150 seconds

  4. 140 seconds

  5. None of these
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Train A speed is 36 km/hr = 10 m/s. Length of A = 10 m/s * 20 s = 200 m. Train B length = 200 + 100 = 300 m. Train B speed = 18 km/hr = 5 m/s. Time to cross 500 m platform = (300 + 500) / 5 = 800 / 5 = 160 seconds.

AI explanation

Convert the speed of train A to 10 m/s using the 5/18 conversion factor. Since it crosses a pole in 20 seconds, its length is 10 m/s multiplied by 20 seconds, giving 200 m. Train B is 100 m longer, so its length is 300 m, making the total distance to cross the 500 m platform 800 m. Train B travels at 18 km/hr, which converts to 5 m/s, so dividing the 800 m distance by 5 m/s gives a time of 160 seconds.

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