document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=641718>Question 641718</A>: <I><SPAN STYLE=\"word-break: break-all;\"> A car travels 120 miles per hour from point A to B at 30mph.  Then, travels back at 40 mph.  What was the cars average speed for the whole trip? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #403777 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=403777\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> A car travels 120 miles per hour from point A to B at 30mph.  Then, travels back at 40 mph.  What was the cars average speed for the whole trip?<BR>\n" );
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document.write( "Travels at 40 mi/hr for how long, or how far?<BR>\n" );
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document.write( "A car travels 120 miles per hour from point A to B at 30mph.<BR>\n" );
document.write( "What speed is it?  120 or 30?<BR>\n" );
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document.write( "I think you meant:<BR>\n" );
document.write( "A car travels 120 miles from point A to B at 30mph.  Then, travels back at 40 mph.  What was the cars average speed for the whole trip?<BR>\n" );
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document.write( "t = d/r = 120/30 + 120/40<BR>\n" );
document.write( "t = 7 hrs<BR>\n" );
document.write( "avg = 240/7 mi/hr<BR>\n" );
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document.write( "The distance for a round trip is not relevant.<BR>\n" );
document.write( "RT avg speed = 2*30*40/(30+40) = 240/7<BR>\n" );
document.write( "It's similar to parallel resistance or parallel flows, but with with a factor of 2.\r<BR>\n" );
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