document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=998632>Question 998632</A>: <I><SPAN STYLE=\"word-break: break-all;\"> I really need help with this question this is a two part question but I feel if you show me step by step how you got your answer then I will be able to try the other one.  Find the time it takes for $9,400 to double when invested at an annual interest rate of 13%, compounded continuously. Please show the years. I came up with approximately 5.3 years but the answer was wrong. thanks </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #616403 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=616403\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> rule of 72: doubles in 72/13; 72 divided by interest rate which would be about 5.54 years.The rule of 72 slightly overestimates the time to double.  It applies in this case.<BR>\n" );
document.write( "P=Poexp^rt<BR>\n" );
document.write( "P/Po=2, which is doubling.<BR>\n" );
document.write( "2=exp^rt<BR>\n" );
document.write( "ln 2=rt<BR>\n" );
document.write( "ln2/r=t<BR>\n" );
document.write( "0.693/0.13 =t<BR>\n" );
document.write( "t=5.33 years </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );