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QIn calm water, a man may swim at a speed of 10 kilometres per hour. When he swims up the river, it takes him twice as long as when he swims down the river to reach his target. How fast is the river flowing?
ID: #4718
Time and Distance
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#4718Q ID
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Time and DistanceTopic
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The speed of the river is X km/hr, and the man has a downward speed of 10 + X km/hr when he swims with the flow of the river, and an upward speed of 10 - X km/hr when he swims against the flow. The problem states that the time it takes the man to cover a distance Y when he swims up the river is double the time it takes him to cover the same distance when he swims down the river. To solve for the speed of the river, we can set up the following equation: Y/(10-X) = 2 * Y/(10+X) We can then solve for X as follows: 10Y + XY = 20Y - 2XY XY + 2XY = 20Y - 10Y 3XY = 10Y 3X = 10 X = 10/3 = <<10/3=3.333>>3.333 km/hr Therefore, the speed of the river is approximately 3.333 km/hr.
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