document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=253874>Question 253874</A>: <I><SPAN STYLE=\"word-break: break-all;\"> beryllium-11 decomposes into boron-11 with a half life of 13.8 seconds.  How long will it take 240 g of beryllium-11 to decompose into 7.5g of beryllium-11? \r<BR>\n" );
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document.write( "based on the forumula provided in the text book C(t)=C(0)2e^-t/h\r<BR>\n" );
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document.write( "where C(0) = 240, C(t)=7.5 ,h=13.8\r<BR>\n" );
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document.write( "7.5/240=2e^-t/13.8\r<BR>\n" );
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document.write( "this was a s far as i got </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #853054 by </B><A HREF=/tutors/aboutme.mpl?userid=ikleyn><B>ikleyn(53339)</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=853054\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> .<BR>\n" );
document.write( "Beryllium-11 decomposes into boron-11 with a half life of 13.8 seconds. <BR>\n" );
document.write( "How long will it take 240 g of beryllium-11 to decompose into 7.5 g of berlyium-11?<BR>\n" );
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document.write( "This problem is very special and very specific.\r<BR>\n" );
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document.write( "For the complete solution, &nbsp;there is &nbsp;NO &nbsp;NEED &nbsp;to write many-store complicated exponential functions.\r<BR>\n" );
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document.write( "There is a special method and a special approach/reasoning, &nbsp;and this problem <BR>\n" );
document.write( "is &nbsp;SPECIALLY &nbsp;CREATED &nbsp;for you to learn this special solution method from me.\r<BR>\n" );
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document.write( "Notice that  the ratio  &nbsp;&nbsp;<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=240%2F7.5 ALIGN=MIDDLE  ALT=\"240%2F7.5\"   DISABLED_style= \"max-width:90%; height:auto;\" >  &nbsp;&nbsp;is  &nbsp;&nbsp;32.\r<BR>\n" );
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document.write( "&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;It means that &nbsp;5 &nbsp;(five) half-lives happened in this decay process\r<BR>\n" );
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document.write( "&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;from 240 gram of Beryllium-11 to 7.5 grams of Beryllium-11, &nbsp;because  &nbsp;&nbsp;<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=2%5E5 ALIGN=MIDDLE  ALT=\"2%5E5\"   DISABLED_style= \"max-width:90%; height:auto;\" > = 32.\r<BR>\n" );
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document.write( "5 &nbsp;half-lives is &nbsp;5 &nbsp;times &nbsp;13.8 &nbsp;seconds,  &nbsp;or  &nbsp;5 * 13.8 = 69 seconds.\r<BR>\n" );
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document.write( "<U>ANSWER</U>.  &nbsp;&nbsp;It will take &nbsp;69 seconds for 240 grams of &nbsp;&nbsp;Beryllium-11 &nbsp;to decompose into &nbsp;7.5 grams of Beryllium-11.<BR>\n" );
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document.write( "&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Solved and explained in a way how it &nbsp;SHOULD &nbsp;be done \r<BR>\n" );
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document.write( "&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;and how it is &nbsp;EXPECTED &nbsp;to be done.\r<BR>\n" );
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document.write( " </SPAN>\n" );
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