Multiple choice

If it takes 20 seconds for a train to cross a 60 meters long platform, and a man standing on platform observes that it took 16 seconds for train to cross him. Find the speed of train.

  1. 36 kmph

  2. 45 kmph

  3. 50 kmph

  4. 54 kmph

  5. 65 kmph
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D Correct answer
Explanation

Let L be train length, v be speed. L/v = 16. (L+60)/v = 20. L = 16v. (16v+60)/v = 20 => 16 + 60/v = 20 => 60/v = 4 => v = 15 m/s. 15 m/s = 15 * 18/5 kmph = 54 kmph.

AI explanation

Using the formula speed equals distance divided by time, let the train length be L and its speed be S. From the man crossing, L equals 16 times S. When crossing the 60 m platform in 20 seconds, L plus 60 equals 20 times S. Substituting 16 times S for L gives 16 times S plus 60 equals 20 times S, so S is 15 m/s. Multiplying 15 by 3.6 converts the speed to 54 kmph.

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