document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=148605>Question 148605</A>: <I><SPAN STYLE=\"word-break: break-all;\"> A culture of yeast doubles in size every 20 minutes. The size of the culture is now N0. Find its size in 12 hours. How do you solve these problems?<BR>\n" );
document.write( "Sugar is put in a large quantity of water and the mixture is stirred. After 2 minutes, 50% of the sugar has dissolved. How much longer will it take until 90% of the sugar has dissolved? <BR>\n" );
document.write( "I am really having trouble and I need your assistance. </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #108955 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=108955\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\">  A culture of yeast doubles in size every 20 minutes. The size of the culture is now No. Find its size in 12 hours.<BR>\n" );
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document.write( "A(t) = No(2)^(t/20) where t is the number of hours<BR>\n" );
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document.write( "A(12) = No(2)^(12*(60/20)) = No*2^36 = appox. 6.87..x 10^10*No<BR>\n" );
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document.write( "Sugar is put in a large quantity of water and the mixture is stirred. After 2 minutes, 50% of the sugar has dissolved. How much longer will it take until 90% of the sugar has dissolved? <BR>\n" );
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document.write( "If 50% has dissolved after 2 minutes, 50% remains after two minutes.<BR>\n" );
document.write( "You want to know how long till only 10% of No remains.<BR>\n" );
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document.write( "EQUATION:<BR>\n" );
document.write( "When does No(1/2)^(x/2) = 0.1No<BR>\n" );
document.write( "(1/2)^(x/2) = 0.10<BR>\n" );
document.write( "Take the log of both sides to get:<BR>\n" );
document.write( "(x/2)*log(1/2) = log 0.1<BR>\n" );
document.write( "(x/2) = 3.321928...<BR>\n" );
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document.write( "Number of minutes = 2*3.321978.. = 6.643856...<BR>\n" );
document.write( "This is total time including the 1st two minutes.<BR>\n" );
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document.write( "Cheers,<BR>\n" );
document.write( "Stan H.\r<BR>\n" );
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