document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1183698>Question 1183698</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Hi<BR>\n" );
document.write( "A certain journey took 40min to complete. If half the distance was travelled at an average speed of 100km per hour and the  other half at an average speed of 60km per hour, what was the length of the journey. <BR>\n" );
document.write( "Thanks<BR>\n" );
document.write( "Textbook says its 24km.<BR>\n" );
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document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #814154 by </B><A HREF=/tutors/aboutme.mpl?userid=greenestamps><B>greenestamps(13200)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=greenestamps><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=greenestamps><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=814154\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> <br><BR>\n" );
document.write( "Certainly the textbook answer you show is not right. 24km in 40 minutes means an average speed of (24/(2/3))=36km/h.  That's not possible if the speeds for the two halves of the trip were 100km/h and 60km/h.<br><BR>\n" );
document.write( "Here is an approach to the problem very different from the one shown by the other tutor.<br><BR>\n" );
document.write( "The two distances are the same; the ratio of the two speeds is 100:60=5:3.<br><BR>\n" );
document.write( "That means the times spent at the two speeds are in the ratio 3:5.<br><BR>\n" );
document.write( "So 3/8 of the 40 minutes was spent at 100km/h and 5/8 of the 40 minutes at 60km/h.  The total distance was then<br><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=100%28%283%2F8%29%2840%2F60%29%29%2B60%28%285%2F8%29%2840%2F60%29%29+=+25%2B25+=+50 ALIGN=MIDDLE  ALT=\"100%28%283%2F8%29%2840%2F60%29%29%2B60%28%285%2F8%29%2840%2F60%29%29+=+25%2B25+=+50\"   DISABLED_style= \"max-width:90%; height:auto;\" ><br><BR>\n" );
document.write( "ANSWER: 50km<br><BR>\n" );
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