Multiple choice

A boat covers 35 km downstream in 2 h and covers the same distance upstream in 7 h. Find the speed (in km/h) of the boat in still water.

  1. 11.25

  2. 28.75

  3. 18.25

  4. 10.55
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A Correct answer
Explanation

Downstream speed = 35/2 = 17.5 km/h. Upstream speed = 35/7 = 5 km/h. Boat speed = (17.5 + 5)/2 = 22.5/2 = 11.25 km/h.

AI explanation

The downstream speed of the boat is 35 km divided by 2 hours, which equals 17.5 km/h. The upstream speed is 35 km divided by 7 hours, which equals 5 km/h. Using the formula for the speed of a boat in still water, we average these two speeds: (17.5 + 5) divided by 2 equals 11.25 km/h.

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