Multiple choice

In each of the following questions, a question is followed by three statements numbered I, II and III. Read all the statements and find which information is/are necessary to answer. What is the speed of the train? I. Length of the train is 300 meters. II. The train crosses a platform double of its length in 54 sec. III. The train crosses a signal pole in 18 sec

  1. All three together are sufficient

  2. II and III together

  3. I and III together

  4. All three together are not sufficient

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

From Statement I and III: Length = 300m, crosses pole in 18s. Speed = 300/18 = 50/3 m/s. From II and III: Platform length = 2*train length. Crosses in 54s, so 3*length = speed*54. Also crosses pole in 18s, so length = speed*18. Solving: 3*18*speed = 54*speed, consistent. Speed = 50/3 m/s. Both (I,III) and (II,III) work, so E is correct.

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