document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1187528>Question 1187528</A>: <I><SPAN STYLE=\"word-break: break-all;\"> A research person made 160 mg of radioactive sodium and found that there was only 20 mg left 45 hours later. what is the half life of radioactive sodium? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #818523 by </B><A HREF=/tutors/aboutme.mpl?userid=ikleyn><B>ikleyn(52798)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=ikleyn><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=ikleyn><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=818523\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> .<BR>\n" );
document.write( "A research person made 160 mg of radioactive sodium and found that there was only 20 mg left 45 hours later. what is the half life of radioactive sodium?<BR>\n" );
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document.write( "Notice that  20 mg = <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=%281%2F8%29%2A160 ALIGN=MIDDLE  ALT=\"%281%2F8%29%2A160\"   DISABLED_style= \"max-width:90%; height:auto;\" > mg,  and  <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=1%2F8 ALIGN=MIDDLE  ALT=\"1%2F8\"   DISABLED_style= \"max-width:90%; height:auto;\" > = <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=1%2F2%5E3 ALIGN=MIDDLE  ALT=\"1%2F2%5E3\"   DISABLED_style= \"max-width:90%; height:auto;\" >.\r\n" );
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document.write( "It means that 45 hours comprise of 3 half-life periods.\r\n" );
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document.write( "So, one half-life period is one third of 45 hours, i.e. 15 hours.\r\n" );
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document.write( "<U>ANSWER</U>.  Half-life is 15 hours.\r\n" );
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document.write( "Solved and explained.\r<BR>\n" );
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document.write( "On radioactive decay, &nbsp;see the lesson\r<BR>\n" );
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document.write( "&nbsp;&nbsp;&nbsp;&nbsp;- <A  rel=nofollow HREF=https://www.algebra.com/algebra/homework/logarithm/Radioactive-decay-problems.lesson>Radioactive decay problems</A> \r<BR>\n" );
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document.write( "in this site.\r<BR>\n" );
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document.write( "You will find many similar &nbsp;(and different) &nbsp;solved problems there.\r<BR>\n" );
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document.write( "&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Use this lesson as your handbook, &nbsp;textbook, &nbsp;guide, &nbsp;tutorials, and &nbsp;(free of charge) &nbsp;home teacher.\r<BR>\n" );
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document.write( "&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Learn the subject from there once and for all.\r<BR>\n" );
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document.write( "Also, &nbsp;you have this free of charge online textbook in &nbsp;ALGEBRA-I &nbsp;in this site\r<BR>\n" );
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document.write( "&nbsp;&nbsp;&nbsp;&nbsp;- <A  rel=nofollow HREF=https://www.algebra.com/algebra/homework/quadratic/lessons/ALGEBRA-I-YOUR-ONLINE-TEXTBOOK.lesson>ALGEBRA-I - YOUR ONLINE TEXTBOOK</A>.\r<BR>\n" );
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document.write( "The referred lesson is the part of this online textbook under the topic \"<U>Logarithms</U>\".\r<BR>\n" );
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document.write( "Save the link to this online textbook together with its description\r<BR>\n" );
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document.write( "Free of charge online textbook in ALGEBRA-I<BR>\n" );
document.write( "https://www.algebra.com/algebra/homework/quadratic/lessons/ALGEBRA-I-YOUR-ONLINE-TEXTBOOK.lesson\r<BR>\n" );
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document.write( "to your archive and use it when it is needed.\r<BR>\n" );
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document.write( " </SPAN>\n" );
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