document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=608787>Question 608787</A>: <I><SPAN STYLE=\"word-break: break-all;\"> The half life of a particular radioactive isotape of thorium is 8 minute.  Find an exponential decay equation for this isotope of the form y= ae^-kt where t is in minutes. </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #383372 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=383372\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> The half life of a particular radioactive isotape of thorium is 8 minute. Find an exponential decay equation for this isotope of the form y= ae^-kt where t is in minutes.<BR>\n" );
document.write( "------<BR>\n" );
document.write( "y = a*e^(-kt)<BR>\n" );
document.write( "---<BR>\n" );
document.write( "If \"a\" is the original amt. of isotope, a/2 is 1/2*a.<BR>\n" );
document.write( "---<BR>\n" );
document.write( "Solve for \"k\":<BR>\n" );
document.write( "a/2 = a*e^(-kt)<BR>\n" );
document.write( "e^(-kt) = 1/2<BR>\n" );
document.write( "(-kt) = ln(1/2)<BR>\n" );
document.write( "---<BR>\n" );
document.write( "(-8k) = -0.6931<BR>\n" );
document.write( "k = 0.0866<BR>\n" );
document.write( "----<BR>\n" );
document.write( "Equation:<BR>\n" );
document.write( "y = a*e^(-0.0866t)<BR>\n" );
document.write( "=======================<BR>\n" );
document.write( "Cheers,<BR>\n" );
document.write( "Stan H. </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );