Question 1056912: A motorboat goes downstream in a river and covers the distance between two coastal towns in 5 hours. It covers this distance upstream in 6 hours. If the speed of the stream is 2 km/h, find the speed of the boat in still water.
Answer by ikleyn(52775)   (Show Source):
You can put this solution on YOUR website! .
A motorboat goes downstream in a river and covers the distance between two coastal towns in 5 hours.
It covers this distance upstream in 6 hours. If the speed of the stream is 2 km/h, find the speed of the boat in still water.
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Let "u" be the boat speed in still water, in km/h.
Then the boat speed downstream is (u+2) km/h, and the distance downstream is
5*(u+2) kilometers. (The distance = rate*time, as you know).
The boat speed upstream is (u-2) km/h, and the distance upstream is
6*(u-2) kilometers.
Since the distance downstream is the same as upstream, you have this equation
5(u+2) = 6(u-2).
Simplify and solve it for "u". You will get the answer u = 22 km/h.
Answer. The speed of the boat in still water is 22 km/h.
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