document.write( "Question 679495: Bill paddled a canoe 2 miles upstream in a river that has a current of 2 mph. He then turned around and paddled downstream until he reached his original starting place. If the entire trip took him 7 hours, how fast would Bill paddle in still water? \n" ); document.write( "

Algebra.Com's Answer #421965 by stanbon(75887) $\"\"$ $\"About$

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Bill paddled a canoe 2 miles upstream in a river that has a current of 2 mph. He then turned around and paddled downstream until he reached his original starting place. If the entire trip took him 7 hours, how fast would Bill paddle in still water?
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\n" ); document.write( "Let his still-water rate be \"r\":
\n" ); document.write( "Let his distance be \"x\" for each leg of the journey:
\n" ); document.write( "---
\n" ); document.write( "Equation:
\n" ); document.write( "time + time = 7 hrs
\n" ); document.write( "2/(r+2)+2/(r-2) = 7
\n" ); document.write( "2(r-2) + 2(r+2) = 7(r^2-4)
\n" ); document.write( "----
\n" ); document.write( "4r = 7r^2 - 28
\n" ); document.write( "------
\n" ); document.write( "7r^2 - 4r - 28 = 0
\n" ); document.write( "Positive solution using Quadratic formula:
\n" ); document.write( "r = 2.306.. mph
\n" ); document.write( "--------------------
\n" ); document.write( "Cheers,
\n" ); document.write( "Stan H. \n" ); document.write( "

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