document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=333459>Question 333459</A>: <I><SPAN STYLE=\"word-break: break-all;\"> A school has a telephone system for letting parents know about emergency school closing. The system is a pyramid with five layers. Three parents are on top layer of the pyramid. Each parent in each layer calls three different parents. How many parents are in the chain?  </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #238971 by </B><A HREF=/tutors/aboutme.mpl?userid=jrfrunner><B>jrfrunner(365)</B></A><img src=\"/images/stars/stars-10.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=jrfrunner><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=jrfrunner><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=238971\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> at layer k there are 3^k parents, where k=1 to 5<BR>\n" );
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document.write( "total = <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=sum+%283%5Ek%29 ALIGN=MIDDLE  ALT=\"sum+%283%5Ek%29\"   DISABLED_style= \"max-width:90%; height:auto;\" > k=1 to 5<BR>\n" );
document.write( "total =<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=%283%5E%285%2B1%29-3%29%2F%283-1%29=%283%5E6-3%29%2F2=363 ALIGN=MIDDLE  ALT=\"%283%5E%285%2B1%29-3%29%2F%283-1%29=%283%5E6-3%29%2F2=363\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
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document.write( "note: <BR>\n" );
document.write( "In general<BR>\n" );
document.write( "total = <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=sum+%28r%5Ek%29 ALIGN=MIDDLE  ALT=\"sum+%28r%5Ek%29\"   DISABLED_style= \"max-width:90%; height:auto;\" > k=1 to n <BR>\n" );
document.write( "total =<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=%28r%5E%28n%2B1%29-r%29%2F%28r-1%29 ALIGN=MIDDLE  ALT=\"%28r%5E%28n%2B1%29-r%29%2F%28r-1%29\"   DISABLED_style= \"max-width:90%; height:auto;\" > </SPAN>\n" );
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