document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=260017>Question 260017</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Strontium–90 has a half-life of 29 years. How long will it take for an initial sample of 10 mg to decay to 1 mg?\r<BR>\n" );
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document.write( "Do I use the formula A= Ao(1/2)^t/h<BR>\n" );
document.write( "If yes I come up with 1=10(1/2)^t/29 which ends up to be wrong. \r<BR>\n" );
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document.write( "So how do I proceed? Please HELP!!! </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #191460 by </B><A HREF=/tutors/aboutme.mpl?userid=nerdybill><B>nerdybill(7384)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=nerdybill><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=nerdybill><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=191460\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Strontium–90 has a half-life of 29 years. How long will it take for an initial sample of 10 mg to decay to 1 mg? <BR>\n" );
document.write( ".<BR>\n" );
document.write( "You can apply the general \"exponential decay\" modeled by:<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=A+=+Ie%5E%28kt%29 ALIGN=MIDDLE  ALT=\"A+=+Ie%5E%28kt%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "Where<BR>\n" );
document.write( "A is the final amount<BR>\n" );
document.write( "I is the initial amount<BR>\n" );
document.write( "k is a constant<BR>\n" );
document.write( "t is time<BR>\n" );
document.write( ".<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=A+=+Ie%5E%28kt%29 ALIGN=MIDDLE  ALT=\"A+=+Ie%5E%28kt%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "Plugging in your given information to first find k:<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=%281%2F2%2910+=+10e%5E%28k%2A29%29 ALIGN=MIDDLE  ALT=\"%281%2F2%2910+=+10e%5E%28k%2A29%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=5+=+10e%5E%28k%2A29%29 ALIGN=MIDDLE  ALT=\"5+=+10e%5E%28k%2A29%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=1%2F2+=+e%5E%28k%2A29%29 ALIGN=MIDDLE  ALT=\"1%2F2+=+e%5E%28k%2A29%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=ln%281%2F2%29+=+29k ALIGN=MIDDLE  ALT=\"ln%281%2F2%29+=+29k\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=ln%281%2F2%29%2F29+=+k ALIGN=MIDDLE  ALT=\"ln%281%2F2%29%2F29+=+k\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=-.0239016+=+k ALIGN=MIDDLE  ALT=\"-.0239016+=+k\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( ".<BR>\n" );
document.write( "Now, your actual model is:<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=A+=+Ie%5E%28-.0239016t%29 ALIGN=MIDDLE  ALT=\"A+=+Ie%5E%28-.0239016t%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( ".<BR>\n" );
document.write( "And we can use to to answer your question.<BR>\n" );
document.write( "How long will it take for an initial sample of 10 mg to decay to 1 mg? <BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=A+=+Ie%5E%28-.0239016t%29 ALIGN=MIDDLE  ALT=\"A+=+Ie%5E%28-.0239016t%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=1+=+10e%5E%28-.0239016t%29 ALIGN=MIDDLE  ALT=\"1+=+10e%5E%28-.0239016t%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=.1+=+e%5E%28-.0239016t%29 ALIGN=MIDDLE  ALT=\".1+=+e%5E%28-.0239016t%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=ln%28.1%29+=+-.0239016t ALIGN=MIDDLE  ALT=\"ln%28.1%29+=+-.0239016t\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=ln%28.1%29%2F-.0239016+=+t ALIGN=MIDDLE  ALT=\"ln%28.1%29%2F-.0239016+=+t\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "96.34 yrs = t </SPAN>\n" );
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