document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1187907>Question 1187907</A>: <I><SPAN STYLE=\"word-break: break-all;\"> A ferry leaves a harbor and travels to a resort island at an average speed of 18 mph. On the return trip, because of fog, the ferry travels at an average speed of 10 mph. The total time for the trip is 7 h. How far is the island from the harbor? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #818919 by </B><A HREF=/tutors/aboutme.mpl?userid=greenestamps><B>greenestamps(13200)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=greenestamps><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=greenestamps><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=818919\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> <br><BR>\n" );
document.write( "(1) A standard algebraic setup for solving the problem....<br><BR>\n" );
document.write( "d = distance (miles)<br><BR>\n" );
document.write( "d/18 = time (hours) for outbound trip at 18mph<BR>\n" );
document.write( "d/10 = time (hours) for return trip at 10mph<br><BR>\n" );
document.write( "The total time is 7 hours:<br><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=d%2F18%2Bd%2F10=7 ALIGN=MIDDLE  ALT=\"d%2F18%2Bd%2F10=7\"   DISABLED_style= \"max-width:90%; height:auto;\" ><br><BR>\n" );
document.write( "Solve using basic algebra....<br><BR>\n" );
document.write( "Multiply by the least common denominator, 90:<br><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=5d%2B9d=630 ALIGN=MIDDLE  ALT=\"5d%2B9d=630\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=14d=630 ALIGN=MIDDLE  ALT=\"14d=630\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=d=630%2F14=90%2F2=45 ALIGN=MIDDLE  ALT=\"d=630%2F14=90%2F2=45\"   DISABLED_style= \"max-width:90%; height:auto;\" ><br><BR>\n" );
document.write( "ANSWER: 45 miles<br><BR>\n" );
document.write( "(2) An informal solution using logical reasoning and simple mental arithmetic....<br><BR>\n" );
document.write( "The distances out and back are the same, so the ratio of the times spent on the two legs of the trip is the same as the ratio of the two speeds.<br><BR>\n" );
document.write( "The ratio of speeds for the first and second legs is 18:10 = 9:5.<br><BR>\n" );
document.write( "So the ratio of times spent on the first and second legs is 5:9.<br><BR>\n" );
document.write( "The total time was 7 hours, so<br><BR>\n" );
document.write( "time spent on outbound leg: (5/14)(7) hours = 2.5 hours<BR>\n" );
document.write( "time spent on return leg: (9/14)(7) hours = 4.5 hours<br><BR>\n" );
document.write( "Length of each leg:<BR>\n" );
document.write( "(2.5 hours)*(18mph) = 45 miles<BR>\n" );
document.write( "or<BR>\n" );
document.write( "(4.5 hours)*(10mph) = 45 miles<br><BR>\n" );
document.write( "ANSWER: 45 miles<br><BR>\n" );
document.write( " </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );