document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=704411>Question 704411</A>: <I><SPAN STYLE=\"word-break: break-all;\"> the speed of the current in a river is 6 mph.  A ferry operator who works that part of the river is looking to buy a new boat.  Every day, his route takes him 22.5 miles against the current and back to his dock, and he needs to make this trip in a total of 9 hours.  he has a boat in mind, but he can only test in on a lake where there is no current.  How fast must the boat go on the lake in order for it to serve the ferry operator's needs?  No idea where to start.  thanks </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #434074 by </B><A HREF=/tutors/aboutme.mpl?userid=josmiceli><B>josmiceli(19441)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=josmiceli><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=josmiceli><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=434074\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> This is kind of a trick question, but really, it's supposed<BR>\n" );
document.write( "to make you think. When you travel 22.5 miles against<BR>\n" );
document.write( "the current, and then back the current opposes you one way<BR>\n" );
document.write( "and assists you the other way, so the effects cancel.<BR>\n" );
document.write( "So, the operators time on a lake with no current is the same<BR>\n" );
document.write( "as the time going up and down the river.<BR>\n" );
document.write( "---------------<BR>\n" );
document.write( "Let <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+s+ ALIGN=MIDDLE  ALT=\"+s+\"   DISABLED_style= \"max-width:90%; height:auto;\" > = the speed of the boat on the lake<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+s+=+%28+2%2A22.5+%29+%2F+9+ ALIGN=MIDDLE  ALT=\"+s+=+%28+2%2A22.5+%29+%2F+9+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+s+=+45+%2F+9+ ALIGN=MIDDLE  ALT=\"+s+=+45+%2F+9+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+s+=+5+ ALIGN=MIDDLE  ALT=\"+s+=+5+\"   DISABLED_style= \"max-width:90%; height:auto;\" > <BR>\n" );
document.write( "He needs to go 5 mi/hr on the lake for the <BR>\n" );
document.write( "boat to work on the river also<BR>\n" );
document.write( " </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );