document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=940487>Question 940487</A>: <I><SPAN STYLE=\"word-break: break-all;\"> An artifact was found and tested for its carbon-14 content. If 77% of the original carbon-14 was still present, what is its probable age (to the nearest 100 years)? (Carbon-14 has a half-life of 5,730 years.)<BR>\n" );
document.write( " </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #573248 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=573248\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> An artifact was found and tested for its carbon-14 content.<BR>\n" );
document.write( " If 77% of the original carbon-14 was still present, what is its probable age (to the nearest 100 years)?<BR>\n" );
document.write( " (Carbon-14 has a half-life of 5,730 years.)<BR>\n" );
document.write( ":<BR>\n" );
document.write( "The radioactive decay formula: A = Ao(2^(-t/h)), where:<BR>\n" );
document.write( "A = amt present after t time<BR>\n" );
document.write( "Ao = initial amt (t=0)<BR>\n" );
document.write( "t = time of decay<BR>\n" );
document.write( "h = half-life of substance<BR>\n" );
document.write( ":<BR>\n" );
document.write( "Let initial amt = 1, then A = .77<BR>\n" );
document.write( "1(2^(-t/5730)) = .77<BR>\n" );
document.write( "using natural logs<BR>\n" );
document.write( "ln(2^(-t/5730)) = ln(.77)<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%2F5730 ALIGN=MIDDLE  ALT=\"-t%2F5730\"   DISABLED_style= \"max-width:90%; height:auto;\" >ln(2) = ln(.77)<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=-t%2F5730 ALIGN=MIDDLE  ALT=\"-t%2F5730\"   DISABLED_style= \"max-width:90%; height:auto;\" > = <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=ln%28.77%29%2Fln%282%29 ALIGN=MIDDLE  ALT=\"ln%28.77%29%2Fln%282%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( " use a calc<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=-t%2F5730 ALIGN=MIDDLE  ALT=\"-t%2F5730\"   DISABLED_style= \"max-width:90%; height:auto;\" > = -.377<BR>\n" );
document.write( "multiply both sides by -5730<BR>\n" );
document.write( "t = -5730 * -.377<BR>\n" );
document.write( "t = +2160 ~ 2200 yrs </SPAN>\n" );
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