A person goes downstream at x km/h and upstream at y km/h by the same boat. What is the ratio of speed of boat in still water to speed of water ?

  1. A. \frac{x}{y}
  2. B. \frac{y}{x}
  3. C. \frac{(x+y)}{(x-y)}
  4. D. \frac{(x-y)}{(x+y)}

Correct Answer: C. \frac{(x+y)}{(x-y)}

Explanation

Speed of boat = (Downstream Speed + Upstream Speed) / 2 = (x + y) / 2. Speed of water = (Downstream Speed - Upstream Speed) / 2 = (x - y) / 2. The ratio is (x + y) : (x - y).

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