SOLUTION: A motorboat took 3 hours to make a downstream trip with a current of 6km/h. The return trip against the same current took 5 hours. Find the speed of the boat in still water.

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Question 162845: A motorboat took 3 hours to make a downstream trip with a current of 6km/h. The return trip against the same current took 5 hours. Find the speed of the boat in still water.
Answer by orca(409) About Me  (Show Source):
You can put this solution on YOUR website!
Let x be the speed in still water.
Then the downstream speed relative to land is x + 6, and
the upstream speed relative to land is x - 6.
the distance traveled downstream = 3(x + 6)
the distance traveled downstream = 5(x - 6)
Now use the following relationship to set up an equation:
the distance traveled downstream = the distance traveled upstream.
So
3(x + 6) = 5(x - 6)
Solving the equation for x, we have
3x + 18 = 5x - 30
48 = 2x
24 = x
Thus x = 24
So the speed in still water is 24 km/h