document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1095972>Question 1095972</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Can I just ask if 7 hours is a correct answer or nah? I'm kinda confused and is unsure of my process.Thank you. :)\r<BR>\n" );
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document.write( "A drug is eliminated from the body through urine. Suppose that for a dose of 10 milligrams, the amount A(t) remaining in the body t hours later is given by A(t)=10(0.8)^t and that in order for the drug to be effective, at least 2 milligrams must be in the body. Determine when 2 milligrams is left in the body.\r<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 #710439 by </B><A HREF=/tutors/aboutme.mpl?userid=Boreal><B>Boreal(15235)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=Boreal><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=Boreal><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=710439\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> A(t)=10(0.8)^t; A(t) must be at least 2.<BR>\n" );
document.write( "2=10(0.8)^t<BR>\n" );
document.write( "2/10=0.8^t<BR>\n" );
document.write( "0.2=0.8^t<BR>\n" );
document.write( "take ln both sides<BR>\n" );
document.write( "ln (0.2)=t ln (0.8) by property of logs<BR>\n" );
document.write( "t=ln(0.2)/ln(0.8)<BR>\n" );
document.write( "t=7.21 hours\r<BR>\n" );
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