document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1167511>Question 1167511</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Amanda leaves Boston at 10:00 AM and drives to Buffalo, NY, which is 400 miles away. After 4 hours, the traffic causes Amanda to reduce her speed by 20 mph. She stops to rest for two hours, and then arrives in Buffalo at 8:00 PM.<BR>\n" );
document.write( "What was Amanda's initial speed? <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 #792131 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=792131\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> <br><BR>\n" );
document.write( "You should know how to solve the problem using formal algebra, as shown by the other tutor.<br><BR>\n" );
document.write( "However, if a formal algebraic solution is not required, and/or if you want to get some good practice in logical thinking (and thus give your brain some good exercise), this problem lends itself to a quick and easy solution.<br><BR>\n" );
document.write( "The total trip was 10 hours; she stopped for a rest for 2 hours, so the total driving time was 8 hours.<br><BR>\n" );
document.write( "So her average speed was 400/8 = 50 mph.<br><BR>\n" );
document.write( "She drove for 4 hours at her original speed, so she drove for 4 hours at the reduced speed.<br><BR>\n" );
document.write( "Since she drove equal amounts of time at the two speeds, her overall average of 50 mph was halfway between her two driving speeds.<br><BR>\n" );
document.write( "Since the difference between the two speeds was 20 mph, an overall average of 50 mph means the two speeds were 50+10=60 and 50-10=40 mph.<br><BR>\n" );
document.write( "ANSWER: Her original speed was 60 mph.<br><BR>\n" );
document.write( "CHECK:<BR>\n" );
document.write( "4 hours at 60 mph, plus 4 hours at 40 mph, equals 400 miles<BR>\n" );
document.write( "4(60)+4(40) = 240+160 = 400<br><BR>\n" );
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