document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1171695>Question 1171695</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Coffee contains caffeine. The half-life of caffeine is 5 hours. This means the amount of caffeine in your bloodstream is reduced by 50% every 5 hours. Suppose you drink a cup of coffee that contains 320 mg of caffeine. How long will it take until there is 5 mg of caffeine left in your bloodstream? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #796606 by </B><A HREF=/tutors/aboutme.mpl?userid=Boreal><B>Boreal(15235)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=Boreal><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=Boreal><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=796606\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> the half-life is 5 hours.<BR>\n" );
document.write( "5/320=1/64 which is 2^-6, or (1/2)^6<BR>\n" );
document.write( "(1/2)^6=1/64<BR>\n" );
document.write( "6 half-lives or 30 hours.<BR>\n" );
document.write( "320-160(5)-80(10)-40(15)-20(20)-10(25)-5(30) </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );