document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1085268>Question 1085268</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Ed is a runner and he runs a 8 km loop every day.  The first 4 km, he<BR>\n" );
document.write( "runs at 12km/hr.  He runs much slower on the way home.  If it takes him 1 hour in total to<BR>\n" );
document.write( "run the loop, how fast is he running for the last 4 km? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #699334 by </B><A HREF=/tutors/aboutme.mpl?userid=jim_thompson5910><B>jim_thompson5910(35256)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=jim_thompson5910><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/images/nopicture.jpg><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=699334\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> <font color=\"black\" face=\"times\" size=\"4\">The formula we'll use here is<BR>\n" );
document.write( "d = r*t<BR>\n" );
document.write( "where,<BR>\n" );
document.write( "d = distance<BR>\n" );
document.write( "r = rate (aka speed)<BR>\n" );
document.write( "t = time\r<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( "If Ed runs 4 km and his speed is 12 km/hr, then d = 4 and r = 12. Plug these values into the formula above and solve for t<BR>\n" );
document.write( "d = r*t<BR>\n" );
document.write( "4 = 12*t<BR>\n" );
document.write( "4/12 = 12*t/12<BR>\n" );
document.write( "1/3 = t<BR>\n" );
document.write( "t = 1/3\r<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( "So it takes Ed 1/3 of an hour, which is (1/3)*60 = 20 minutes to run the 4 km.\r<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( "20 minutes pass by when Ed runs the first 4 km, leaving 60 - 20 = 40 minutes left over.\r<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( "40 minutes = 40*(1/60) = 40/60 = 4/6 = 2/3 of an hour\r<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( "So we'll use t = 2/3 and d = 4 to find the rate (r)\r<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( "d = r*t<BR>\n" );
document.write( "4 = r*(2/3)<BR>\n" );
document.write( "3*4 = 3*r*(2/3) ... multiply both sides by 3<BR>\n" );
document.write( "12 = 2r<BR>\n" );
document.write( "2r = 12<BR>\n" );
document.write( "2r/2 = 12/2 ... divide both sides by 2<BR>\n" );
document.write( "r = 6\r<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( "Therefore, Ed's speed on the last four kilometers is <font color=red>6 km/hr</font> which is the final answer.</font> </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );