document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=985285>Question 985285</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Athlete Amazing Al strolled, walked, jogged and sprinted around four equal sides of a city block.  His speeds on each side were 4 km/h, 5 km/h, 10 km/h and 20 km/h.\r<BR>\n" );
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document.write( "What was Amazing Al's average speed for the whole city block? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #606109 by </B><A HREF=/tutors/aboutme.mpl?userid=Boreal><B>Boreal(15235)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=Boreal><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=Boreal><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=606109\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Assume the block is 4 km on a side.<BR>\n" );
document.write( "It took 60 minutes to do the first leg, 48 minutes to do the second, 24 minutes to do the third, and 12 minutes to do the fourth.<BR>\n" );
document.write( "That is 144 minutes to do 16 km=6 2/3 km/h<BR>\n" );
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document.write( "With speed problems, be very careful not to average the four speeds, which here would give 9.75 km/h. That is because more time is spent at slower speeds than at faster speeds, and velocity is an inverse function of time for the same distance.  V=D/T\r<BR>\n" );
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document.write( "For x km on a side it is (x/4)+(x/5)+(x/10)+(x/20) units are hr {km/(km/hr)=hr]<BR>\n" );
document.write( "That is  (12x/20)=0.6 x<BR>\n" );
document.write( "So 1 km on a side takes 36 minutes total, and the average speed is 4/0.6=6 2/3 km/h </SPAN>\n" );
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