Multiple choice

What is the speed of the boat in still water if the speed of the boat in still water is 350% of the speed of the stream? Statement I: It takes 2 hours to cover a distance between A and B downstream. Statement II: It takes 4 hours to cover a distance between A and B upstream.

  1. If the data in statement I alone are sufficient to answer the question, while the data in statement II alone are not sufficient to answer the question

  2. If the data in statement II alone are sufficient to answer the question, while the data in statement I alone are not sufficient to answer the question.

  3. If the data either in statement I alone or in statement II alone are sufficient to answer the question.

  4. If the data even in both statements I and II together are not sufficient to answer the question.

  5. If the data in both statements I and II together are necessary to answer the question.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The question has a contradiction: it asks to find boat speed in still water, then states it equals 350% of stream speed. If we knew stream speed, we'd have the answer. Statement I: Downstream speed = Boat + Stream. Distance/time = D/2. Statement II: Upstream speed = Boat - Stream = D/4. We have two equations but three unknowns (D, Boat speed, Stream speed). Even combined, we cannot solve for boat speed without knowing distance D. From given condition: Boat = 3.5 * Stream. But we still have 2 equations with 2 unknowns (D, Stream). Actually: D/2 = 3.5S + S = 4.5S, and D/4 = 3.5S - S = 2.5S. So D = 9S and D = 10S. This is impossible (9S ≠ 10S unless S=0). Contradiction means data is inconsistent/insufficient. Option D correct.

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