SOLUTION: The current in a stream moves at a rate of 4 mph. If a boat travels 56 miles downstream in the same time that it takes to travel 28 miles upstream, what is the speed of the boat in

Algebra ->  Equations -> SOLUTION: The current in a stream moves at a rate of 4 mph. If a boat travels 56 miles downstream in the same time that it takes to travel 28 miles upstream, what is the speed of the boat in      Log On


   

Question 1162087: The current in a stream moves at a rate of 4 mph. If a boat travels 56 miles downstream in the same time that it takes to travel 28 miles upstream, what is the speed of the boat in still water?
Found 2 solutions by ikleyn, Alan3354:
Answer by ikleyn(52777) About Me  (Show Source):
You can put this solution on YOUR website!
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From the condition, you have this equation


56%2F%28u%2B4%29 = 28%2F%28u-4%29,


where U is the speed of the boat in still water.


Notice that each side of the equation is the corresponding traveled time.


Reduce the common factor 28 in both sides; then cross multiply.  You will get


    2*(u-4) = u + 4

    2u - 8 = u + 4

    2u - u = 4 + 8

     u     = 12.


ANSWER.  The speed of the boat is 12 miles per hour in still water.

Solved.


Answer by Alan3354(69443) About Me  (Show Source):
You can put this solution on YOUR website!
The current in a stream moves at a rate of 4 mph.
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Actually, the current doesn't move. The water moves.
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The speed of the current is 4 mi/hr.