document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=849684>Question 849684</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Mike started a savings account by depositing $9. Each month he deposits more money than the month before. At the end of 41 months, he has saved $9,989.00. How much more does he deposit each month?  </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #511696 by </B><A HREF=/tutors/aboutme.mpl?userid=swincher4391><B>swincher4391(1107)</B></A><img src=\"/images/stars/stars-12.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=swincher4391><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=swincher4391><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=511696\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> sum of arithmetic series:\r<BR>\n" );
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document.write( "Sn = (a1 + an) * n / 2\r<BR>\n" );
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document.write( "= (9+an)*41/2 = 9989\r<BR>\n" );
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document.write( "solving for An we get \r<BR>\n" );
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document.write( "An = 478.27\r<BR>\n" );
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document.write( "An = A1 + (n-1)*d  where d is the common difference\r<BR>\n" );
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document.write( "478.27 = 9 + (41-1)*d\r<BR>\n" );
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document.write( "478.27 - 9 = 40d\r<BR>\n" );
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document.write( "469.27 = 40d\r<BR>\n" );
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document.write( "d = <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=highlight%2811.73%29 ALIGN=MIDDLE  ALT=\"highlight%2811.73%29\"   DISABLED_style= \"max-width:90%; height:auto;\" > <BR>\n" );
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