document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=841973>Question 841973</A>: <I><SPAN STYLE=\"word-break: break-all;\"> A radioactive substance has a halflife of 120 years. If 200mg of substance was present, how much of the substance remains after 340 years? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #507334 by </B><A HREF=/tutors/aboutme.mpl?userid=josgarithmetic><B>josgarithmetic(39623)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=josgarithmetic><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=507334\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Decay Equation in general, <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=A=Ie%5E%28-kt%29 ALIGN=MIDDLE  ALT=\"A=Ie%5E%28-kt%29\"   DISABLED_style= \"max-width:90%; height:auto;\" >.<BR>\n" );
document.write( "A = amount after time t<BR>\n" );
document.write( "I = initial amount when t=0<BR>\n" );
document.write( "k = a constant<BR>\n" );
document.write( "At half-life, <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=%281%2F2%29=e%5E%28-kt%29 ALIGN=MIDDLE  ALT=\"%281%2F2%29=e%5E%28-kt%29\"   DISABLED_style= \"max-width:90%; height:auto;\" > and you would want to find k for a given or known t.<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=ln%281%2F2%29=-kt ALIGN=MIDDLE  ALT=\"ln%281%2F2%29=-kt\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=k=-%28ln%281%2F2%29%29%2Ft ALIGN=MIDDLE  ALT=\"k=-%28ln%281%2F2%29%29%2Ft\"   DISABLED_style= \"max-width:90%; height:auto;\" >\r<BR>\n" );
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document.write( "You are given that t=120 for the half life and so you can calculate and find the value for k. </SPAN>\n" );
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