document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1143472>Question 1143472</A>: <I><SPAN STYLE=\"word-break: break-all;\"> An unknown radioactive element decays into non-radioactive substances. In <BR>\n" );
document.write( "700 days the radioactivity of a sample decreases by 29 percent. \r<BR>\n" );
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document.write( "(a) What is the half-life of the element? <BR>\n" );
document.write( "half-life:  <BR>\n" );
document.write( "    (days) \r<BR>\n" );
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document.write( "(b) How long will it take for a sample of <BR>\n" );
document.write( "100mg to decay to 54mg? <BR>\n" );
document.write( "time needed: <BR>\n" );
document.write( "             (days)  </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #764278 by </B><A HREF=/tutors/aboutme.mpl?userid=josgarithmetic><B>josgarithmetic(39617)</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=764278\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> ---------------------------------------------<BR>\n" );
document.write( "In 700 days the radioactivity of a sample decreases by 29 percent. <BR>\n" );
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document.write( "??\r<BR>\n" );
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document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=y=pe%5E%28-kx%29 ALIGN=MIDDLE  ALT=\"y=pe%5E%28-kx%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "-<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=ln%28y%29=ln%28p%29-kx ALIGN=MIDDLE  ALT=\"ln%28y%29=ln%28p%29-kx\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=ln%28y%29-ln%28p%29=-kx ALIGN=MIDDLE  ALT=\"ln%28y%29-ln%28p%29=-kx\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=kx=ln%28p%29-ln%28y%29 ALIGN=MIDDLE  ALT=\"kx=ln%28p%29-ln%28y%29\"   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%28p%29-ln%28y%29%29%2Fx ALIGN=MIDDLE  ALT=\"k=%28ln%28p%29-ln%28y%29%29%2Fx\"   DISABLED_style= \"max-width:90%; height:auto;\" >\r<BR>\n" );
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document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=k=%28ln%28p%2Fy%29%29%2Fx ALIGN=MIDDLE  ALT=\"k=%28ln%28p%2Fy%29%29%2Fx\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "-\r<BR>\n" );
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document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=k=ln%28100%2F71%29%2F700 ALIGN=MIDDLE  ALT=\"k=ln%28100%2F71%29%2F700\"   DISABLED_style= \"max-width:90%; height:auto;\" >\r<BR>\n" );
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document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=k=0.0004893 ALIGN=MIDDLE  ALT=\"k=0.0004893\"   DISABLED_style= \"max-width:90%; height:auto;\" >\r<BR>\n" );
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document.write( "-<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=highlight_green%28y=pe%5E%28-0.0004893x%29%29 ALIGN=MIDDLE  ALT=\"highlight_green%28y=pe%5E%28-0.0004893x%29%29\"   DISABLED_style= \"max-width:90%; height:auto;\" >\r<BR>\n" );
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document.write( "HALF-LIFE\r<BR>\n" );
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document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=x%5Bhalf%5D=ln%282%29%2Fk ALIGN=MIDDLE  ALT=\"x%5Bhalf%5D=ln%282%29%2Fk\"   DISABLED_style= \"max-width:90%; height:auto;\" >\r<BR>\n" );
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document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=x%5Bhalf%5D=ln%282%29%2F0.0004893 ALIGN=MIDDLE  ALT=\"x%5Bhalf%5D=ln%282%29%2F0.0004893\"   DISABLED_style= \"max-width:90%; height:auto;\" >\r<BR>\n" );
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document.write( "1416 </SPAN>\n" );
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