document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1077704>Question 1077704</A>: <I><SPAN STYLE=\"word-break: break-all;\"> A radioactive substance is known to decay at a rate proportional to the amount<BR>\n" );
document.write( "present. If half of a given sample has disappeared after 1200 years, find ( to the<BR>\n" );
document.write( "nearest percent) what percentage remains after 1800 years.  </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #692186 by </B><A HREF=/tutors/aboutme.mpl?userid=jorel1380><B>jorel1380(3719)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=jorel1380><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=jorel1380><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=692186\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Half the mass lost is:<BR>\n" );
document.write( "1/2=e^-kt where k is a constant, and t is the time. In this case,our substances' half life is 1200, so:<BR>\n" );
document.write( "-0.69314718055994530941723212145818=-1200k<BR>\n" );
document.write( "k=0.000577622650466621<BR>\n" );
document.write( "e^-(0.0005776226504666211)1800=35.355339059327375658806198307235% of the mass remaining after 1800 years. &#9786;&#9786;&#9786;&#9786;  </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );