document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=177441>Question 177441</A>: <I><SPAN STYLE=\"word-break: break-all;\"> My daughter missed this class friday and has a final monday morning..can you please show how to get answer and correct answer?  Superman has a violent reaction to red kryptonite which decays into green krytonite with a half life of 5 hours.  Red Kryptonite is no longer dangerous to Superman when 90 percent of the red kryptonite has decayed.<BR>\n" );
document.write( "a.  What percent of the kryptonite is left after one day?<BR>\n" );
document.write( "b.  how long before the red kryptonite has decayed 90 percent and is safe for superman?\r<BR>\n" );
document.write( "\n" );
document.write( "Thank you for your help! </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #132585 by </B><A HREF=/tutors/aboutme.mpl?userid=Fombitz><B>Fombitz(32388)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=Fombitz><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=Fombitz><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=132585\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> a.)If you start with 100% and the half life is 5 hours<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=N%28t%29=N%5B0%5D%2Ae%5E%28-alpha%2At%29 ALIGN=MIDDLE  ALT=\"N%28t%29=N%5B0%5D%2Ae%5E%28-alpha%2At%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "where <BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=alpha=ln%282%29%2Ft%5Bhl%5D=ln%282%29%2F5=0.1386 ALIGN=MIDDLE  ALT=\"alpha=ln%282%29%2Ft%5Bhl%5D=ln%282%29%2F5=0.1386\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "Then for t=24 hours,<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=N%28t%29=N%5B0%5D%2Ae%5E%28-alpha%2At%29 ALIGN=MIDDLE  ALT=\"N%28t%29=N%5B0%5D%2Ae%5E%28-alpha%2At%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=N%2824%29=N%5B0%5D%2Ae%5E%28-0.1386%2A24%29 ALIGN=MIDDLE  ALT=\"N%2824%29=N%5B0%5D%2Ae%5E%28-0.1386%2A24%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=N%2824%29=100%2A0.0359 ALIGN=MIDDLE  ALT=\"N%2824%29=100%2A0.0359\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=N%2824%29=3.59 ALIGN=MIDDLE  ALT=\"N%2824%29=3.59\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "3.59% remains at 24 hours.<BR>\n" );
document.write( "b.)Start with 100%. Find t when 90% will be gone, 10% will remain.<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=N%28t%29=N%5B0%5D%2Ae%5E%28-alpha%2At%29 ALIGN=MIDDLE  ALT=\"N%28t%29=N%5B0%5D%2Ae%5E%28-alpha%2At%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=10=100%2Ae%5E%28-0.1386%2At%29 ALIGN=MIDDLE  ALT=\"10=100%2Ae%5E%28-0.1386%2At%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=e%5E%28-0.1386%2At%29=0.1 ALIGN=MIDDLE  ALT=\"e%5E%28-0.1386%2At%29=0.1\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=-0.1386%2At=ln%280.1%29 ALIGN=MIDDLE  ALT=\"-0.1386%2At=ln%280.1%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=-0.1386%2At=-2.303 ALIGN=MIDDLE  ALT=\"-0.1386%2At=-2.303\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=t=-2.303%2F0.1386 ALIGN=MIDDLE  ALT=\"t=-2.303%2F0.1386\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=t=16.6 ALIGN=MIDDLE  ALT=\"t=16.6\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "After 16.6 hours, there will be 10% left.<BR>\n" );
document.write( " </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );