document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=457268>Question 457268</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Page 548 # 1<BR>\n" );
document.write( " Police use blood alcohol content (ABC) to measure the percent concentration of alcohol in a person’s bloodstream. In most states, a BAC of 0.08 percent means person is not allowed to drive. Each hour after drinking, a person’s ABC may decrease by 15%. If a person has BAC of 0.18, how many hours will he need to wait he can legally drive? <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 #313755 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=313755\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> In most states, a BAC of 0.08 percent means person is not allowed to drive. Each hour after drinking, a person’s ABC may decrease by 15%. If a person has BAC of 0.18, how many hours will he need to wait he can legally drive? <BR>\n" );
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document.write( "Start 0.18<BR>\n" );
document.write( "After 1 hr: 0.18-0.15*0.18 = (1-0.15)0.18 = 0.85*0.18<BR>\n" );
document.write( "After 2 hr: 0.85^2*0.18<BR>\n" );
document.write( "etc.<BR>\n" );
document.write( "----<BR>\n" );
document.write( "Solve:<BR>\n" );
document.write( "0.85^n(0.18) < 0.08<BR>\n" );
document.write( "---<BR>\n" );
document.write( "0.85^n < 0.08/0.18 = 0.4444<BR>\n" );
document.write( "n > log(0.4444)/log(0.85)<BR>\n" );
document.write( "n > 4.9899<BR>\n" );
document.write( "n >= 5 hrs.<BR>\n" );
document.write( "=================<BR>\n" );
document.write( "Cheers,<BR>\n" );
document.write( "Stan H.  </SPAN>\n" );
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