Multiple choice

The ratio of speeds of boat with the stream and against the stream is 5 : 2, respectively. If the speed of boat in still water is 14 kmph, then what is the speed of stream?

  1. 6 kmph

  2. 8 kmph

  3. 10 kmph

  4. None of these
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Let boat speed be B and stream speed be S. (B+S)/(B-S) = 5/2. Given B = 14, (14+S)/(14-S) = 5/2. 28 + 2S = 70 - 5S, so 7S = 42, S = 6.

AI explanation

Let the common ratio be x, making the downstream speed 5x and the upstream speed 2x. Using the formula for the speed of a boat in still water, (downstream speed + upstream speed) / 2, we have (5x + 2x) / 2 = 14. Solving gives 7x / 2 = 14, so x = 4. The downstream speed is 20 kmph and the upstream speed is 8 kmph. Using the stream speed formula, (downstream speed - upstream speed) / 2, the speed is (20 - 8) / 2 = 6 kmph.

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