document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=835134>Question 835134</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Harry's motorboat can make an average of 8 miles per hour. One day he sets out for a trip, only to have the motor break down. Harry rows back at two miles an hour. When he reaches his dock, he finds that he has been gone 5 hours. How far has he rowed?\r<BR>\n" );
document.write( "\n" );
document.write( "The equation is 8x = 10 - 2x.<BR>\n" );
document.write( "Tried this:<BR>\n" );
document.write( "8x = 10 - 2x + 2x<BR>\n" );
document.write( "8x + 2x = 10x <BR>\n" );
document.write( "10x = 10\r<BR>\n" );
document.write( "\n" );
document.write( "Also if anybody has some tips on recognizing equations in word problems. Thank You :)<BR>\n" );
document.write( " </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #503387 by </B><A HREF=/tutors/aboutme.mpl?userid=Alan3354><B>Alan3354(69443)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=Alan3354><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=Alan3354><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=503387\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Harry's motorboat can make an average of 8 miles per hour. One day he sets out for a trip, only to have the motor break down. Harry rows back at two miles an hour. When he reaches his dock, he finds that he has been gone 5 hours. How far has he rowed?<BR>\n" );
document.write( "---------------------<BR>\n" );
document.write( "The formula for the average speed of a round trip is<BR>\n" );
document.write( "avg = 2*r1*r2/(r1 + r2)<BR>\n" );
document.write( "---<BR>\n" );
document.write( "avg = 2*8*2/(8 + 2) = 32/10<BR>\n" );
document.write( "avg = 3.2 mi/hr<BR>\n" );
document.write( "---<BR>\n" );
document.write( "d = r*t = 3.2*5 = 16 miles round trip, 8 miles each way.<BR>\n" );
document.write( "--------------------<BR>\n" );
document.write( "I don't recommend trying to memorize a formula for all problems, but this one is similar to parallel flows, parallel resistors, etc, just with a factor of 2 for the round trip.<BR>\n" );
document.write( "Notice it's independent of the distance.<BR>\n" );
document.write( "-----<BR>\n" );
document.write( "It was the basis of the Michelson-Morley experiment in the 1840's which showed that there was no effect of the \"ether.\"  \r<BR>\n" );
document.write( "\n" );
document.write( "The existence of the ether was used to explain how light from the Sun could travel. The ether was the medium theorized.\r<BR>\n" );
document.write( "\n" );
document.write( "The lack of effect disproved the existence of the ether, and it was put away in the closet with phlogiston.<BR>\n" );
document.write( " </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );