document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1199250>Question 1199250</A>: <I><SPAN STYLE=\"word-break: break-all;\"> The half-life of a radioactive substance is one hundred twenty-five days. How many days will it take for eighty-two percent of the substance to decay?\r<BR>\n" );
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document.write( "A. 180<BR>\n" );
document.write( "B. 367<BR>\n" );
document.write( "C. 275<BR>\n" );
document.write( "D. 310<BR>\n" );
document.write( "E. 532<BR>\n" );
document.write( "F. 426 </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #833054 by </B><A HREF=/tutors/aboutme.mpl?userid=MathTherapy><B>MathTherapy(10552)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=MathTherapy><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=MathTherapy><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=833054\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> <BR>\n" );
document.write( "The half-life of a radioactive substance is one hundred twenty-five days. How many days will it take for eighty-two percent of the substance to decay?\r<BR>\n" );
document.write( "\n" );
document.write( "A. 180<BR>\n" );
document.write( "B. 367<BR>\n" );
document.write( "C. 275<BR>\n" );
document.write( "D. 310<BR>\n" );
document.write( "E. 532<BR>\n" );
document.write( "F. 426<BR>\n" );
document.write( "<PRE STYLE=\"white-space: pre-wrap; white-space: -moz-pre-wrap; white-space: -pre-wrap; white-space: -o-pre-wrap; word-wrap: break-word;\">If \"a\" is given as the <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=1%2F2 ALIGN=MIDDLE  ALT=\"1%2F2\"   DISABLED_style= \"max-width:90%; height:auto;\" >-life of a substance, the DECAY CONSTANT, or <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=matrix%282%2C3%2C+k%2C+%22=%22%2C+ln%281%2F2%29%2Fa%2C+k%2C+%22=%22%2C+ln%281%2F2%29%2F125%29 ALIGN=MIDDLE   DISABLED_style= \"max-width:90%; height:auto;\" >. This calculates to -0.005545177, or - .00554\r\n" );
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document.write( "                                             As 82% (.82) decayed, remainder is 18% (100 - 82). \r\n" );
document.write( "                                   CONTINUOUS GROWTH/DECAY formula: <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=matrix%283%2C3%2C+A%2C+%22=%22%2C+A%5B0%5De%5E%28kt%29%2C+A%2FA%5Bo%5D%2C+%22=%22%2C+e%5E%28kt%29%2C+.18%2C+%22=%22%2C+e%5E%28-+.00554t%29%29 ALIGN=MIDDLE   DISABLED_style= \"max-width:90%; height:auto;\" >\r\n" );
document.write( "                                                               - .00554t = ln(.18) ----- Converting to LOGARITHMIC (Natural) form\r\n" );
document.write( "<font color = red><font size = 4><b>Time taken for 82% of substance to decay</font></font></b>, or <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=matrix%281%2C10%2C+t%2C+%22=%22%2C+ln%28.18%29%2F%28-+.00554%29%2C+%22=%22%2C+309.5304022%2C+or%2C+highlight%28310%29%2C%22%28ROUNDED%22%2C+%22UP%29%22%2C+days%29%29 ALIGN=MIDDLE   DISABLED_style= \"max-width:90%; height:auto;\" ></PRE> </SPAN>\n" );
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