document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=272215>Question 272215</A>: <I><SPAN STYLE=\"word-break: break-all;\"> The averages speed of an automobile for the first half of a 100 km. trip was <BR>\n" );
document.write( "60 km/hr and from the second half was 90 km/hr. What was the average speed in <BR>\n" );
document.write( "km/hr for the entire distance?\r<BR>\n" );
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document.write( "(A) 68   (B) 72   (C) 75   D) 78   (E) 80<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 #199191 by </B><A HREF=/tutors/aboutme.mpl?userid=ptaylor><B>ptaylor(2198)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=ptaylor><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=ptaylor><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=199191\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Distance(d) equals Rate(r) times Time(t) or d=r/t; r=d/t and t=d/r\r<BR>\n" );
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document.write( "Average Speed=(Total Distance)/(Total Time)<BR>\n" );
document.write( "Total Distance = 100km<BR>\n" );
document.write( "Total Time=Time for the 1st half + Time for the 2nd half<BR>\n" );
document.write( "Time for the 1st half=50/60=5/6 hr<BR>\n" );
document.write( "Time for the 2nd half=50/90=5/9 hr<BR>\n" );
document.write( "So,<BR>\n" );
document.write( "Average Speed=100/(5/6+5/9)<BR>\n" );
document.write( "Average Speed=100/(15/18 +10/18)<BR>\n" );
document.write( "Average Speed=100/(25/18) multiply numerator and denominator by 18/25<BR>\n" );
document.write( "Average Speed=100(18/25)/1=4*18=72 km/hr\r<BR>\n" );
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document.write( "Hope this helps---ptaylor </SPAN>\n" );
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