document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1006212>Question 1006212</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Sodium-24 is a radioactive isotope of sodium that is used to study circulatory dysfunction. Assuming that 4 micrograms of sodium-24 are injected into a person, the amount A in micrograms remaining in that person after t hours is given by the equation A = 4e^&#8722;0.046t.\r<BR>\n" );
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document.write( "(b) What amount of sodium-24 remains after 8 hours? (Round your answer to two decimal places.)<BR>\n" );
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document.write( "=µg\r<BR>\n" );
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document.write( "(c) What is the half-life of sodium-24? (Round your answer to two decimal places.)<BR>\n" );
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document.write( "=h\r<BR>\n" );
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document.write( "(d) In how many hours will the amount of sodium-24 be 1 microgram? (Round your answer to two decimal places.)<BR>\n" );
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document.write( "=h </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #622360 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=622360\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> The decay model written better, <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=highlight_green%28A=4e%5E%28-0.046t%29%29 ALIGN=MIDDLE  ALT=\"highlight_green%28A=4e%5E%28-0.046t%29%29\"   DISABLED_style= \"max-width:90%; height:auto;\" >.\r<BR>\n" );
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document.write( "(b)<BR>\n" );
document.write( "After 8 hours, just plug-in t=8 and compute A.\r<BR>\n" );
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document.write( "(c)<BR>\n" );
document.write( "Very simply choose <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=1%2F2=1%2Ae%5E%28-0.046%2At%29 ALIGN=MIDDLE  ALT=\"1%2F2=1%2Ae%5E%28-0.046%2At%29\"   DISABLED_style= \"max-width:90%; height:auto;\" > to find half-life.<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=ln%281%2F2%29=ln%281%29%2B%28-0.046t%29ln%28e%29 ALIGN=MIDDLE  ALT=\"ln%281%2F2%29=ln%281%29%2B%28-0.046t%29ln%28e%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%282%29=0-0.046t%2A1 ALIGN=MIDDLE  ALT=\"-ln%282%29=0-0.046t%2A1\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=ln%282%29=0.046t ALIGN=MIDDLE  ALT=\"ln%282%29=0.046t\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=highlight%28t=ln%282%29%2F0.046%29 ALIGN=MIDDLE  ALT=\"highlight%28t=ln%282%29%2F0.046%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "Compute to<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=highlight%28t=15%29 ALIGN=MIDDLE  ALT=\"highlight%28t=15%29\"   DISABLED_style= \"max-width:90%; height:auto;\" >, in HOURS\r<BR>\n" );
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document.write( "(d)<BR>\n" );
document.write( "This is similar to finding half-life.<BR>\n" );
document.write( "You want A=1, and again find logarithms of both sides of the decay equation, to<BR>\n" );
document.write( "solve for t.<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=ln%281%29=ln%284%29%2B%28-0.046t%29ln%28e%29 ALIGN=MIDDLE  ALT=\"ln%281%29=ln%284%29%2B%28-0.046t%29ln%28e%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=0=ln%284%29-0.046t ALIGN=MIDDLE  ALT=\"0=ln%284%29-0.046t\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=0.046t=ln%284%29 ALIGN=MIDDLE  ALT=\"0.046t=ln%284%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=highlight_green%28t=ln%284%29%2F0.046%29 ALIGN=MIDDLE  ALT=\"highlight_green%28t=ln%284%29%2F0.046%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "and you can finish the computing.<BR>\n" );
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