The speed of the boat in still water is 20 km / h, and the speed of the river is 2 km / h. How long will a motorboat

| September 4, 2021 | education

The speed of the boat in still water is 20 km / h, and the speed of the river is 2 km / h. How long will a motorboat spend from one pier to another back, if the distance between the marinas is 198 km?

1. Known boat speed in still water 20 km / h.

The speed of the river is 2 km / h.

This means that the boat moves downstream at a speed of 20 + 2 = 22 km / h.

And against the flow of the river at a speed of 20 – 2 = 18 km / h.

2. The distance between the piers has been determined and is 198 km.

Let’s calculate how long it takes for the boat to sail this distance downstream.

198/22 = 9 hours.

3. Determine the time, how long the boat will move this way against the current.

198/18 = 11 hours.

4. Find the elapsed time.

9 + 11 = 20 hours.

Answer: The boat will take 20 hours.



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