document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=199791>Question 199791</A>: <I><SPAN STYLE=\"word-break: break-all;\"> You drive to the mailbox down the road at 35 mph, slip a letter in, turn around, and drive back at 25 mph.  What is your average speed?  (Note that it is not 30 mph, and you do not need to know the distance.) I tried this but don't know where I am going wrong.\r<BR>\n" );
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document.write( "T (going)= D/35\r<BR>\n" );
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document.write( "and for the return trip\r<BR>\n" );
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document.write( "T(returning) = D/25\r<BR>\n" );
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document.write( "The total time for the trip is T(going) +T(returning) = D/35 + D/25 and you can find the average speed by dividing the total distance 2*D, by the total time:\r<BR>\n" );
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document.write( "V(average) = 2D/(D/35+D/25)\r<BR>\n" );
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document.write( "	V(average)=   1/(1/35 + 1/25)<BR>\n" );
document.write( "			     <BR>\n" );
document.write( "	V(average)= (1*60/1)/(1/60*60/1)<BR>\n" );
document.write( "	V(average)= 60 mph I know this answer is wrong. It doesn't make sense   that it should be the combined speeds.  </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #150173 by </B><A HREF=/tutors/aboutme.mpl?userid=solver91311><B>solver91311(24713)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=solver91311><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=solver91311><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=150173\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> <font face=\"Garamond\" size=\"+2\">\r<BR>\n" );
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document.write( "Actually you were on the right track until you wrote:\r<BR>\n" );
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document.write( "<IMG STYLE=\"max-width:80%;\" SRC=\"/cgi-bin/rendertex.cgi?\LARGE \ \ \ \ \ \ \ \ \ \ V_a = \frac{1}{\frac{1}{35}+\frac{1}{25}}\">\r<BR>\n" );
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document.write( "Which is incorrect.  It should have been:\r<BR>\n" );
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document.write( "<IMG STYLE=\"max-width:80%;\" SRC=\"/cgi-bin/rendertex.cgi?\LARGE \ \ \ \ \ \ \ \ \ \ V_a = \frac{2}{\frac{1}{35}+\frac{1}{25}}\">\r<BR>\n" );
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document.write( "Since you were only taking out a factor of <IMG STYLE=\"max-width:80%;\" SRC=\"/cgi-bin/rendertex.cgi?\Large D\">\r<BR>\n" );
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document.write( "And then how you got from there to:\r<BR>\n" );
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document.write( "<IMG STYLE=\"max-width:80%;\" SRC=\"/cgi-bin/rendertex.cgi?\LARGE \ \ \ \ \ \ \ \ \ \ V_a = \frac{1\cdot\frac{60}{1}}{\frac{1}{60}\cdot\frac{60}{1}\">\r<BR>\n" );
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document.write( "Is completely beyond me.  So lets go back to:\r<BR>\n" );
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document.write( "<IMG STYLE=\"max-width:80%;\" SRC=\"/cgi-bin/rendertex.cgi?\LARGE \ \ \ \ \ \ \ \ \ \ V_a = \frac{2}{\frac{1}{35}+\frac{1}{25}}\">\r<BR>\n" );
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document.write( "The LCD is 175, so:\r<BR>\n" );
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document.write( "<IMG STYLE=\"max-width:80%;\" SRC=\"/cgi-bin/rendertex.cgi?\LARGE \ \ \ \ \ \ \ \ \ \ V_a = \frac{2}{\frac{5}{175}+\frac{7}{175}} = \frac{2}{\frac{12}{175}} = 2\cdot\frac{175}{12} = \frac{175}{6} =29\frac{1}{6}\">\r<BR>\n" );
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document.write( "John<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=\"/cgi-bin/rendertex.cgi?\LARGE e^{i\pi} + 1 = 0\"><BR>\n" );
document.write( "</font> </SPAN>\n" );
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