document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=847275>Question 847275</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Andrew measures the amount of a very unstable substance to be 100 moles. The half life of this substance is three days (after three days, half is gone). \r<BR>\n" );
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document.write( "#1 Write an exponential function that models this situation where y is the amount of substance and x is time in days.\r<BR>\n" );
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document.write( "#2 Use your equation to complete the chart. \r<BR>\n" );
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document.write( "Days                               <BR>\n" );
document.write( "-3(3 days prior)<BR>\n" );
document.write( "0<BR>\n" );
document.write( "3<BR>\n" );
document.write( "6<BR>\n" );
document.write( "12\r<BR>\n" );
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document.write( "Amount (I need to determine the amounts)\r<BR>\n" );
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document.write( "#3 Use your data from the chart to graph your equation. \r<BR>\n" );
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document.write( "#4 Calculate the expected amount of substance if Andrew had taken his measurement 9 days earlier. Show your calculations and consider the trend of your graph.<BR>\n" );
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document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #510310 by </B><A HREF=/tutors/aboutme.mpl?userid=stanbon><B>stanbon(75887)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=stanbon><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=510310\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Andrew measures the amount of a very unstable substance to be 100 moles. The half life of this substance is three days (after three days, half is gone).<BR>\n" );
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document.write( "#1 Write an exponential function that models this situation where y is the amount of substance and x is time in days.<BR>\n" );
document.write( "y = 100*(1/2)^x<BR>\n" );
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document.write( "#2 Use your equation to complete the chart. <BR>\n" );
document.write( "Days <BR>\n" );
document.write( "-3(3 days prior):: y = 100(1/2)^(-3) = 100(1/8) = 12.5<BR>\n" );
document.write( "I'll leave the others to you.\r<BR>\n" );
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document.write( "0<BR>\n" );
document.write( "3<BR>\n" );
document.write( "6<BR>\n" );
document.write( "12 <BR>\n" );
document.write( "Amount (I need to determine the amounts) \r<BR>\n" );
document.write( "\n" );
document.write( "#3 Use your data from the chart to graph your equation.<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=graph%28400%2C400%2C-10%2C10%2C-10%2C10%2C100%281%2F2%29%5Ex%29 ALIGN=MIDDLE  ALT=\"graph%28400%2C400%2C-10%2C10%2C-10%2C10%2C100%281%2F2%29%5Ex%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
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document.write( "#4 Calculate the expected amount of substance if Andrew had taken his measurement 9 days earlier. Show your calculations and consider the trend of your graph.<BR>\n" );
document.write( "y(-9) = 100(1/2)^-9 = 0.1953 moles<BR>\n" );
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document.write( "Cheers,<BR>\n" );
document.write( "Stan H.\r<BR>\n" );
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