document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1189903>Question 1189903</A>: <I><SPAN STYLE=\"word-break: break-all;\"> If money is invested at r percent interest, compounded annually, the amount of the investment will double in approximately 70/r years. If Pat's parents invested $5,000 in a long-term bond that pays 8 percent interest, compounded annually, that will be the approximate total amount of the investment 18 years later, when Pat is ready for college?\r<BR>\n" );
document.write( "\n" );
document.write( "A. $20,000  B. $15,000  C. $12,000  D. $10,000  E. $9,000 </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #821410 by </B><A HREF=/tutors/aboutme.mpl?userid=Theo><B>Theo(13342)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=Theo><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=Theo><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=821410\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> at 8% interest, compounded annually, the money will double in 9.006468342 years.<BR>\n" );
document.write( "the formula is:<BR>\n" );
document.write( "2 = 1.08 ^ n<BR>\n" );
document.write( "take the log of both sides of the equation to get:<BR>\n" );
document.write( "log(2) = n * log(1.08)<BR>\n" );
document.write( "solve for n to get:<BR>\n" );
document.write( "n = log(2) / log(1.08) = 9.006468342.\r<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( "you stated that the money will double in approximately 70/r years.<BR>\n" );
document.write( "the r in your statement would have to be 8 percent, not .08.<BR>\n" );
document.write( "70/8 = 8.75.<BR>\n" );
document.write( "that's pretty close, but  not right on, and lower than what the doubling number of years is.\r<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( "5000 invested at 8% for 18 years would be equal to 5000 * 1.08 ^ 18 = 19980.0975.\r<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( "the formula uses the rate, not the percent.<BR>\n" );
document.write( "the growth factor is 1 plus the rate = 1.08.\r<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( "let me know if this satisfies your inquiry.<BR>\n" );
document.write( "if not, let me know, in more detail, what it is that you're looking for that i'm missing.\r<BR>\n" );
document.write( "<BR>\n" );
document.write( "<BR>\n" );
document.write( "<BR>\n" );
document.write( "<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( " </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );