Multiple choice

A train passes an electric pole in 10 seconds and a platform that is 130 m long in 20 seconds. What is the length of the train?

  1. 130 m

  2. 140 m

  3. 150 m

  4. 160 m

  5. None of these
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A Correct answer
Explanation

Let L be the length of the train and v be its speed. The train covers its own length in 10 seconds (L = 10v) and its length plus the platform in 20 seconds (L + 130 = 20v). Substituting L = 10v into the second equation gives 10v + 130 = 20v, so 10v = 130, meaning L = 130 m.

AI explanation

Let the length of the train be L and its speed be S. Using the formula distance equals speed multiplied by time for the pole, L equals 10S. When passing the 130 m platform, the total distance becomes L plus 130, and the formula gives L plus 130 equals 20S. Substituting 10S for L in the second equation yields 10S plus 130 equals 20S, meaning the speed S is 13 m/s. Multiplying this speed by 10 seconds gives a train length of 130 m. The length of the train is 130 m.

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