Multiple choice

The questions given below contain two statements giving certain data. You have to decide whether the data given in the statements are sufficient for answering the question ? Mark answer - What is the speed of the train ? I. It takes 25 seconds to pass a bridge 1000 m long. II. It takes 10 seconds to pass a pole.

  1. statement I alone is sufficient but statement II alone is not sufficient.

  2. statement II alone is sufficient but statement I alone is not sufficient.

  3. each statement alone (either I or II) is sufficient.

  4. statement I and II together are not sufficient.

  5. both statements together are sufficient, but neither statement alone is sufficient.
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

Speed of train = length of train / time to pass pole. Statement I: 25 seconds for 1000m bridge gives (train length + 1000)/25 = speed, but we need train length. Statement II: 10 seconds to pass pole means train length / 10 = speed, so we can find length from speed, or speed from length. Neither alone gives both. Together: Let length = L. From II: speed = L/10. From I: speed = (L+1000)/25. Equating: L/10 = (L+1000)/25, solving gives L = 666.67m, speed = 66.67 m/s. Both needed.

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