document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=170399>Question 170399</A>: <I><SPAN STYLE=\"word-break: break-all;\"> A certian radioactive substance decays according to the formula A(t)=e^-0.0063t where t is time in days.  What is the half life of this substance (to the nearest day)? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #125802 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=125802\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> A certian radioactive substance decays according to the formula <BR>\n" );
document.write( "A(t) = Aoe^-0.0063t where t is time in days. What is the half life <BR>\n" );
document.write( "of this substance (to the nearest day)?<BR>\n" );
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document.write( "If you start with Ao then A(t) = (1/2)Ao will determine the halflife.<BR>\n" );
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document.write( "(1/2)Ao = Aoe^-0.0063t<BR>\n" );
document.write( "(1/2) = e^-0.0063t<BR>\n" );
document.write( "Take the natural log to get:<BR>\n" );
document.write( "-0.0063t = ln(0.5)<BR>\n" );
document.write( "t = ln(0.5)/-0.0063<BR>\n" );
document.write( "t = 110.0233620 years<BR>\n" );
document.write( "0.0233620*365 days = 8.527.. days<BR>\n" );
document.write( "--------------------<BR>\n" );
document.write( "Ans: Halflife = 110 yrs + 8.527 days<BR>\n" );
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document.write( "Cheers,<BR>\n" );
document.write( "Stan H. </SPAN>\n" );
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