Multiple choice

It takes a boatman 8 hours to cover a distance of 60 km upstream in a river while to cover the same distance in downstream takes 5 hours. What will be the speed of the boatman in still water?

  1. 9.5 kmph

  2. 9.25 kmph

  3. 9.80 kmph

  4. 9.75 kmph
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Let boat speed = u, current speed = c. Upstream: 60/(u-c) = 8, so u-c = 7.5. Downstream: 60/(u+c) = 5, so u+c = 12. Solving: 2u = 19.5, so u = 9.75 km/h. This is the speed in still water.

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