document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1078573>Question 1078573</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Please help me solve this word problem: You invest $100 and expect your money to grow 8% each year. About how many years will it take for your investment to double?<BR>\n" );
document.write( "What function models the growth of your investment?<BR>\n" );
document.write( "How can you use a table to find the approximate amount of time it takes for your investment to double?<BR>\n" );
document.write( "How can you use a graph to find the approximate amount of time it takes for your investment to double? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #693009 by </B><A HREF=/tutors/aboutme.mpl?userid=Boreal><B>Boreal(15235)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=Boreal><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=Boreal><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=693009\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> The rule of 72 would say 9 years. (doubling time in years=72/interest rate in per cent.<BR>\n" );
document.write( "Exactly, it is P=Po(1+.08)^t<BR>\n" );
document.write( "Po is start, P is end<BR>\n" );
document.write( "P/Po therefore equals 2.<BR>\n" );
document.write( "2=1.08^t<BR>\n" );
document.write( "ln2=t ln (1.08)<BR>\n" );
document.write( "t=9.01 years.<BR>\n" );
document.write( "table <BR>\n" );
document.write( "1------1.08<BR>\n" );
document.write( "2------1.08^2=1.1664 etc. until one reaches 2.<BR>\n" );
document.write( "This can be used graphically, and one could draw a curve through the points until 2 is reached for the amount of money. </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );