document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=110865>Question 110865</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Half life question. Please help if possible.\r<BR>\n" );
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document.write( "The half-life of the radioactive element plutonium-239 is 25,000 years. If 16 grams of plutonium-239 are initially present, how many grams are present after 25,000 years? 50,000 years? 75,000 years? 100,000 years? 125,000 years? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #80975 by </B><A HREF=/tutors/aboutme.mpl?userid=ankor@dixie-net.com><B>ankor@dixie-net.com(22740)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=ankor@dixie-net.com><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=ankor@dixie-net.com><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=80975\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> :<BR>\n" );
document.write( "The half-life of the radioactive element plutonium-239 is 25,000 years. If 16 grams of plutonium-239 are initially present, how many grams are present after 25,000 years? <BR>\n" );
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document.write( "The half life formula: A = Ao(2^(-t/h) where<BR>\n" );
document.write( "Ao = original amt<BR>\n" );
document.write( "t = time<BR>\n" );
document.write( "h = half life of the material<BR>\n" );
document.write( "A = resulting amt<BR>\n" );
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document.write( "Substituting for plutonium-239:<BR>\n" );
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document.write( "A = 16(2^(-25000/25000)<BR>\n" );
document.write( "A = 16(2^-1); (you know that 2^-1 = 1/2 or .5, try it on a good calc)<BR>\n" );
document.write( "A = 16 * .5<BR>\n" );
document.write( "A = 8 oz, as you would expect<BR>\n" );
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document.write( "50,000 years?<BR>\n" );
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document.write( "A = 16(2^(-50000/25000)<BR>\n" );
document.write( "A = 16(2^-2); (2^-2) = 1/4)<BR>\n" );
document.write( "A = 16 * .25<BR>\n" );
document.write( "A = 4 oz after 50k yrs<BR>\n" );
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document.write( "75,000 years?<BR>\n" );
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document.write( "A = 16(2^(-75000/25000)<BR>\n" );
document.write( "A = 16(2^-3)<BR>\n" );
document.write( "A = 16 * .125<BR>\n" );
document.write( "A = 2 oz after 75k yrs<BR>\n" );
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document.write( "you should be able to do the rest of them now\r<BR>\n" );
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document.write( "100,000 years? 125,000 years?<BR>\n" );
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