document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=181448>Question 181448</A>: <I><SPAN STYLE=\"word-break: break-all;\"> The level of thorium in a sample decreases by a factor of one-half every 2 million years.  a meteorite is discovered to have only 8.6% of its original thorium remaining. How old is the meteorite? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #136082 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=136082\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> The level of thorium in a sample decreases by a factor of one-half every 2 million years. A meteorite is discovered to have only 8.6% of its original thorium remaining. How old is the meteorite? <BR>\n" );
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document.write( "A(t) = A(0)(1/2)^(t/2 million) where t is in million years<BR>\n" );
document.write( "0.086A(0) = A(o)(1/2)^(t/2)<BR>\n" );
document.write( "0.086 = (1/2)^(t/2)<BR>\n" );
document.write( "Take the log of both sides to get:<BR>\n" );
document.write( "(t/2)*log(1/2) = log(0.086)<BR>\n" );
document.write( "---<BR>\n" );
document.write( "t = 2 <BR>\n" );
document.write( "t = 2* 3.5395... <BR>\n" );
document.write( "t = 7.079.. million years<BR>\n" );
document.write( "=============================<BR>\n" );
document.write( "Cheers,<BR>\n" );
document.write( "Stan H. <BR>\n" );
document.write( " </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );