document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=868686>Question 868686</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Please help me solve this problem.\r<BR>\n" );
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document.write( "A person paddles 1 mi upstream and 1 mile down stream in a total of 1 hour. The speed of the river is 2mph. What is the speed of the persons boat in still water? </SPAN>\n" );
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document.write( "A person paddles 1 mi upstream and 1 mile down stream in a total of 1 hour. The speed of the river is 2mph. What is the speed of the persons boat in still water?<BR>\n" );
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document.write( "Let \"b\" be the speed of the boat in still water.<BR>\n" );
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document.write( "Upstream DATA:<BR>\n" );
document.write( "distance = 1 mile ; rate = b-2 mph ; time = d/r = 1/(b-2) hrs<BR>\n" );
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document.write( "Downstream DATA:<BR>\n" );
document.write( "distance = 1 mile ; rate = b+2 mph ; time = d/r = 1/(b+2) hrs<BR>\n" );
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document.write( "Equation:<BR>\n" );
document.write( "time + time = 1 hr.<BR>\n" );
document.write( "1/(b-2) + 1/(b+2) = 1<BR>\n" );
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document.write( "b+2 + b-2 = b^2-4<BR>\n" );
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document.write( "2b = b^2-4<BR>\n" );
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document.write( "b^2-2b-4 = 0<BR>\n" );
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document.write( "Use the quadratic formula to get:<BR>\n" );
document.write( "b = [2 +- sqrt(4-4*-4)]/2<BR>\n" );
document.write( "b = [2 +- sqrt(20)]/2<BR>\n" );
document.write( "Positive solution::<BR>\n" );
document.write( "b = [2+2sqrt(5)]/2<BR>\n" );
document.write( "b = 1+sqrt(5) <BR>\n" );
document.write( "b = 3.24 mph (speed of the boat in stil water)<BR>\n" );
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document.write( "Cheers,<BR>\n" );
document.write( "Stan H.<BR>\n" );
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document.write( " </SPAN>\n" );
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