document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=960538>Question 960538</A>: <I><SPAN STYLE=\"word-break: break-all;\"> How do you find the current of a river when the paddle boat  takes 57 min to travel 4 miles up and back at a speed10miles per hour? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #587054 by </B><A HREF=/tutors/aboutme.mpl?userid=ankor@dixie-net.com><B>ankor@dixie-net.com(22740)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=ankor@dixie-net.com><IMG SRC=http://www.algebra.com/images/aboutme-small.gif BORDER=0 alt=\"About Me\" VALIGN=MIDDLE></A>&nbsp;<IMG SRC=http://www.algebra.com/cgi-bin/show-face.mpl?user=ankor@dixie-net.com><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=587054\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\">  How do you find the current of a river when the paddle boat takes 57 min to travel 4 miles up and back at a speed 10miles per hour?<BR>\n" );
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document.write( "Let c = the rate of the current<BR>\n" );
document.write( "then<BR>\n" );
document.write( "(10-c) = effective speed up-river<BR>\n" );
document.write( "and<BR>\n" );
document.write( "(10+c) = effective speed down-river<BR>\n" );
document.write( ":<BR>\n" );
document.write( "Convert 57 min to hrs; 57/60<BR>\n" );
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document.write( "Write a time equation, time = dist/speed<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=4%2F%28%2810-c%29%29 ALIGN=MIDDLE  ALT=\"4%2F%28%2810-c%29%29\"   DISABLED_style= \"max-width:90%; height:auto;\" > + <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=4%2F%28%2810%2Bc%29%29 ALIGN=MIDDLE  ALT=\"4%2F%28%2810%2Bc%29%29\"   DISABLED_style= \"max-width:90%; height:auto;\" > = <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=57%2F60 ALIGN=MIDDLE  ALT=\"57%2F60\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "multiply 60(10+c)(10-c)<BR>\n" );
document.write( "60(10+c)(10-c)*<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=4%2F%28%2810-c%29%29 ALIGN=MIDDLE  ALT=\"4%2F%28%2810-c%29%29\"   DISABLED_style= \"max-width:90%; height:auto;\" > + 60(10+c)(10-c)*<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=4%2F%28%2810%2Bc%29%29 ALIGN=MIDDLE  ALT=\"4%2F%28%2810%2Bc%29%29\"   DISABLED_style= \"max-width:90%; height:auto;\" > = 60(10+c)(10-c)<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=57%2F60 ALIGN=MIDDLE  ALT=\"57%2F60\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "cancel the denominators<BR>\n" );
document.write( "60(10+c)*4 + 60(10-c)*4 = 57(10+c)(10-c)<BR>\n" );
document.write( "2400 + 240c + 2400 - 240c = 57(100-c^2)<BR>\n" );
document.write( "4800 = 5700 - 57c^2<BR>\n" );
document.write( "57c^2 = 5700 - 4800<BR>\n" );
document.write( "57c^2 = 900<BR>\n" );
document.write( "c^2 = <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=900%2F57 ALIGN=MIDDLE  ALT=\"900%2F57\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "c = <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=sqrt%2815.789%29 ALIGN=MIDDLE  ALT=\"sqrt%2815.789%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "c = 3.97 ~ 4 mph is the current<BR>\n" );
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document.write( "Check this, find the actual time each way<BR>\n" );
document.write( "4/6 =  .667 hrs<BR>\n" );
document.write( "4/14 = .285 hrs<BR>\n" );
document.write( "----------------<BR>\n" );
document.write( "total: .952 hrs which is .952(60) = 57 min<BR>\n" );
document.write( " </SPAN>\n" );
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