Multiple choice

A boat goes 76 km upstream in 4 hours and 66 km downstream in 2 hours. The speed of the boat in still water is

  1. 26 km/h

  2. 16 km/h

  3. 20 km/h

  4. 8 km/h

  5. None of these
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A Correct answer
Explanation

Upstream speed = 76/4 = 19 km/h. Downstream speed = 66/2 = 33 km/h. Speed in still water is the average of these: (19 + 33) / 2 = 52 / 2 = 26 km/h.

AI explanation

The upstream speed is 76 km divided by 4 hours, which is 19 km/h, and the downstream speed is 66 km divided by 2 hours, which is 33 km/h. Using the formula for the speed of a boat in still water, which is the average of the downstream and upstream speeds, we get (33 + 19) / 2 = 26 km/h.

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