document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=437539>Question 437539</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Use the approximate doubling time formula (rule of 70) for the case described below. Discuss whether the formula is valid for the case described:    \r<BR>\n" );
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document.write( "An economic indicator is increasing at the rate of 7% per year.  What is the doubling time?  By what factor will the indicator increase in 3 years?\r<BR>\n" );
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document.write( "Thank you. </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #302677 by </B><A HREF=/tutors/aboutme.mpl?userid=stanbon><B>stanbon(75887)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=stanbon><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/images/nopicture.jpg><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=302677\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> An economic indicator is increasing at the rate of 7% per year. What is the doubling time? By what factor will the indicator increase in 3 years? <BR>\n" );
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document.write( "A(t) = P(1+(r/n))^(nt)<BR>\n" );
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document.write( "2P = P(1+ (0.07))^t<BR>\n" );
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document.write( "(1.07)^t = 2<BR>\n" );
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document.write( "t = log(2)/log(1.07)<BR>\n" );
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document.write( "t = 10.245 years<BR>\n" );
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document.write( "By what factor will the indicator increase in 3 years? <BR>\n" );
document.write( "Not sure what is meant by that.<BR>\n" );
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document.write( "Cheers,<BR>\n" );
document.write( "Stan H.<BR>\n" );
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