Multiple choice

The speed of a boat in still water is $10$ km/hour if it can travel $26$ km downstream and $14$ Km upstream at the same time, the speed of the stream is

  1. $4$ km/hour
  2. $4.5$ km/hour
  3. $5$ km/hour
  4. $3$ km/hour
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Let stream speed be S. Downstream speed = 10 + S. Upstream speed = 10 - S. Time = distance / speed. 26 / (10 + S) = 14 / (10 - S). 26(10 - S) = 14(10 + S). 260 - 26S = 140 + 14S. 120 = 40S. S = 3.

AI explanation

Let the speed of the stream be v, making the downstream speed 10 + v and the upstream speed 10 - v. Since the time taken is the same, the equation is 26 / (10 + v) = 14 / (10 - v). Cross-multiplying yields 260 - 26v = 140 + 14v, which simplifies to 40v = 120. Solving for v gives 3 km/hour. The result is 3 km/hour.

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