document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1183978>Question 1183978</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Susan invested a total of $10000 in two accounts. One account pays 4 interest and the other account pays 6% Interest. The total retum from both accounts was $560. \r<BR>\n" );
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document.write( "Answer the following questions. \r<BR>\n" );
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document.write( "How much was invested at 4%?<BR>\n" );
document.write( "How much was invested at 6%?\r<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 #814504 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=814504\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> <br><BR>\n" );
document.write( "The other tutor showed a good formal algebraic solution using the standard method.<br><BR>\n" );
document.write( "If a formal algebraic solution is not required, and if the speed of getting an answer is important (as in a timed math competition), then here is a very fast and easy way to solve this problem (and many similar problems) mentally.<br><BR>\n" );
document.write( "(1) $10000 all invested at 4% would yield $400 interest; all at 6% would yield $600 interest.<BR>\n" );
document.write( "(2) The actual interest $560 is 4/5 of the way from $400 to $600.  (Picturing the three numbers 400, 560, and 600 on a number line might help: 400 to 600 is a difference of 200; 400 to 560 is a difference of 160; 160/200 = 4/5.)<BR>\n" );
document.write( "(3) That means 4/5 of the $10000 was invested at the higher rate.<br><BR>\n" );
document.write( "ANSWER: 4/5 of $10000, or $8000, was invested at 6%; the other $2000 at 4%.<br><BR>\n" );
document.write( "CHECK: .06(8000)+.04(2000) = 480+80 = 560<br><BR>\n" );
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