document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1027546>Question 1027546</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Bob can row 9 mph in still water. The total time to travel downstream and return upstream to the starting point is 3 hours and 0 minutes. If the total distance downstream and back is 24 miles, determine the speed of the river (current speed).<BR>\n" );
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document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #642860 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=642860\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Bob can row 9 mph in still water.<BR>\n" );
document.write( " The total time to travel downstream and return upstream to the starting point is 3 hours and 0 minutes.<BR>\n" );
document.write( " If the total distance downstream and back is 24 miles, determine the speed of the river (current speed).<BR>\n" );
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document.write( "let c = the speed of the current<BR>\n" );
document.write( "then<BR>\n" );
document.write( "(9+c) = effective speed downstream<BR>\n" );
document.write( "and<BR>\n" );
document.write( "(9-c) = effective speed up-stream<BR>\n" );
document.write( ":<BR>\n" );
document.write( "Write a time equation; time = dist/speed<BR>\n" );
document.write( "That's 12 mi one-way.<BR>\n" );
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document.write( "Time down + time up = 3 hrs<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=12%2F%289%2Bc%29 ALIGN=MIDDLE  ALT=\"12%2F%289%2Bc%29\"   DISABLED_style= \"max-width:90%; height:auto;\" > + <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=12%2F%289-c%29 ALIGN=MIDDLE  ALT=\"12%2F%289-c%29\"   DISABLED_style= \"max-width:90%; height:auto;\" > = 3<BR>\n" );
document.write( "multiply equation by (9+c)(9-c)<BR>\n" );
document.write( "(9+c)(9-c)*<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=12%2F%289%2Bc%29 ALIGN=MIDDLE  ALT=\"12%2F%289%2Bc%29\"   DISABLED_style= \"max-width:90%; height:auto;\" > + (9+c)(9-c)*<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=12%2F%289-c%29 ALIGN=MIDDLE  ALT=\"12%2F%289-c%29\"   DISABLED_style= \"max-width:90%; height:auto;\" > = 3(9+c)(9-c)<BR>\n" );
document.write( "Cancel the denominators, FOIL the right side<BR>\n" );
document.write( "12(9-c) + 12(9+c) = 3(81 - c^2)<BR>\n" );
document.write( "108 - 12c + 108 + 12c = 243 - 3c^2<BR>\n" );
document.write( "216 = 243 - 3c^2<BR>\n" );
document.write( "3c^2 = 243 - 216<BR>\n" );
document.write( "3c^2 = 27<BR>\n" );
document.write( "c^2 = 27/3<BR>\n" );
document.write( "c^2 = 9<BR>\n" );
document.write( "c = <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=sqrt%289%29 ALIGN=MIDDLE  ALT=\"sqrt%289%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "c = 3 mph is the current<BR>\n" );
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document.write( "See if that checks out, find the actual time each way<BR>\n" );
document.write( "effective speed are 12 mph and 6 mph<BR>\n" );
document.write( "12/12 = 1 hr<BR>\n" );
document.write( "12/6  = 2 hr<BR>\n" );
document.write( "--------------<BR>\n" );
document.write( "total: 3 hrs<BR>\n" );
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