document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=443186>Question 443186</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Estimating the age of a fossil:  A fossilized leaf contains 70% of its normal amount of carbon 14.  How old is the fossil to the nearest year?  Use 5600 years as the half life of carbon 14. </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #305862 by </B><A HREF=/tutors/aboutme.mpl?userid=ankor@dixie-net.com><B>ankor@dixie-net.com(22740)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=ankor@dixie-net.com><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=ankor@dixie-net.com><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=305862\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Estimating the age of a fossil: A fossilized leaf contains 70% of its normal amount of carbon 14.<BR>\n" );
document.write( " How old is the fossil to the nearest year? Use 5600 years as the half life of carbon 14.<BR>\n" );
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document.write( "The radioactive decay formula A = Ao*2^(-t/h)<BR>\n" );
document.write( "where<BR>\n" );
document.write( "A = amt after t yrs<BR>\n" );
document.write( "Ao = initial amt<BR>\n" );
document.write( "h = half-life of substance<BR>\n" );
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document.write( "Assuming initial amt = 1 we have<BR>\n" );
document.write( "1*2^(-t/5600) = .7<BR>\n" );
document.write( "Using nat logs<BR>\n" );
document.write( "ln(2^(-t/500)) = ln(.7)<BR>\n" );
document.write( "log equiv of exponents<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=-t%2F5600 ALIGN=MIDDLE  ALT=\"-t%2F5600\"   DISABLED_style= \"max-width:90%; height:auto;\" >*ln(2) = ln(.7)<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=-t%2F5600 ALIGN=MIDDLE  ALT=\"-t%2F5600\"   DISABLED_style= \"max-width:90%; height:auto;\" > = <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=ln%28.7%29%2Fln%282%29 ALIGN=MIDDLE  ALT=\"ln%28.7%29%2Fln%282%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "using a calc<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=-t%2F5600 ALIGN=MIDDLE  ALT=\"-t%2F5600\"   DISABLED_style= \"max-width:90%; height:auto;\" > = -.51457<BR>\n" );
document.write( "t = -.51457 * -5600<BR>\n" );
document.write( "t = 2881.6 yrs to have 70% left of initial amt<BR>\n" );
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document.write( "Check solution on a calc; enter 2^(-2881.6/5600), results .7000 </SPAN>\n" );
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