document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1155375>Question 1155375</A>: <I><SPAN STYLE=\"word-break: break-all;\"> How long does it take for an investment to double in value if it is invested at 10​% compounded monthly </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #777956 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=777956\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> rule of 70, 7 years is estimate\r<BR>\n" );
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document.write( "P=Po(1+(.10/12))^nt<BR>\n" );
document.write( "P/Po=2<BR>\n" );
document.write( "2=(1+.10/12)^nt<BR>\n" );
document.write( "ln both sides<BR>\n" );
document.write( "ln2=nt(ln (1+.10/12)<BR>\n" );
document.write( "ln2=nt*.008299<BR>\n" );
document.write( "nt=83.52 months rounding at end.<BR>\n" );
document.write( "t=12 because 12 compounding a year<BR>\n" );
document.write( "6 years and 11 1/2 months (rounding), which is close to the 7 year estimate. </SPAN>\n" );
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