document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=154765>Question 154765</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Still don't undertand this and I have a test tomorrow...yikes!!\r<BR>\n" );
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document.write( "Here's the question:\r<BR>\n" );
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document.write( "A picture that was supposedly painted by Vermeer (1632-1675) contains 99.5% of it's carbon=14. The half life for carbon=14 is 5730 years.  Is the picture a fake?\r<BR>\n" );
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document.write( "I know the formula to use is(first, Q_0 = Q-naught) Q=Q_0e^-k5730.  And I know Q should equal 1/2, but I can't seem to put it all together.  Please help!\r<BR>\n" );
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document.write( "Thanks,<BR>\n" );
document.write( "T </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #113967 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=113967\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> not sure about your formula...\r<BR>\n" );
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document.write( "for half-life calculations, you are right - there is a 1/2 in the formula\r<BR>\n" );
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document.write( "A=Ao*(1/2)^(t/h)\r<BR>\n" );
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document.write( "A is the current amount, Ao is the starting amount, t is the time, h is the half-life\r<BR>\n" );
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document.write( "to find the time __ divide by Ao __ A/Ao=.5^(t/h) __ take log __ ln(A/Ao)=(t/h)ln(.5)\r<BR>\n" );
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document.write( "divide by ln(.5) __ [ln(A/Ao)]/[ln(.5)]=t/h __ multiply by h __ h{[ln(A/Ao)]/[ln(.5)]}=t\r<BR>\n" );
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document.write( "5730[ln(.995)/ln(.5)]=t __ 41.4=t (approx) __ doesn't seem old enough </SPAN>\n" );
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