document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=194226>Question 194226</A>: <I><SPAN STYLE=\"word-break: break-all;\"> a piece of bone from an organism is found to contain 10% of the carbon -14 is 5730 years then how long ago was the organism was alive?\r<BR>\n" );
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document.write( "please help me solve!!!!!\r<BR>\n" );
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document.write( "i really dont know how tio solve pleaseeeee help..... </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #145771 by </B><A HREF=/tutors/aboutme.mpl?userid=scott8148><B>scott8148(6628)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=scott8148><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=scott8148><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=145771\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> the half-life of carbon-14 is 5730yr<BR>\n" );
document.write( "this means that in 5730yr, 50% of the original amount will remain<BR>\n" );
document.write( "in another 5730yr, 25% will remain<BR>\n" );
document.write( "and so on\r<BR>\n" );
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document.write( "the number of half-lives can be found from ___ p = (1/2)^n<BR>\n" );
document.write( "where p is the fraction remaining and n is the number of half-lives\r<BR>\n" );
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document.write( "taking the log ___ log(p) = n * log(1/2)<BR>\n" );
document.write( "dividing by log(1/2) ___ [log(p)] / [log(1/2)] = n\r<BR>\n" );
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document.write( "[log(.10)] / [log(1/2)] = n<BR>\n" );
document.write( "using a calculator ___ n = 3.32 (approx)\r<BR>\n" );
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document.write( "so the time is ___ 3.32 * 5730 = 19024yr </SPAN>\n" );
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