document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1139234>Question 1139234</A>: <I><SPAN STYLE=\"word-break: break-all;\"> How long will it take for an investment to double in value if the annual interest rate is 10% and interest is compounded every 4 months? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #757010 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=757010\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> P=Po(1+.10/3)^3n, where n is the number of years.<BR>\n" );
document.write( "Rule of 70 would suggest about 7 years.<BR>\n" );
document.write( "P=2Po for doubling<BR>\n" );
document.write( "so 2=(1+.03333)^3n.<BR>\n" );
document.write( "take ln both sides<BR>\n" );
document.write( "ln2=3n ln(1.03333)<BR>\n" );
document.write( "3n=21.139, dividing ln2 by ln 1.0333 <BR>\n" );
document.write( "n=7.046 years. </SPAN>\n" );
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