document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=986046>Question 986046</A>: <I><SPAN STYLE=\"word-break: break-all;\"> I really need help with this.<BR>\n" );
document.write( "A driving school has 600 trainees. On one particular day, a small group of trainees thought they heard their instructor said that no one one had managed to pass for their advanced driving techniques course. 24 hours later, a survey of the entire student population revealed that by then 40 students had heard this rumour. The rumour spreads according to the equation, R(t)=600/&#12310;1+75e&#12311;^kt    where R(t) is the number of trainees who had heard the rumour, t is the time in hours after the first group of trainees though they heard their instructor and k is a constant.\r<BR>\n" );
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document.write( "Find the time needed for 90% of the trainee population to have heard the rumour.<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 #606799 by </B><A HREF=/tutors/aboutme.mpl?userid=macston><B>macston(5194)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=macston><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=macston><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=606799\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> .<BR>\n" );
document.write( "I cannot decipher your equation, but the process would be:<BR>\n" );
document.write( "Using 40 for R(t) and 24 hrs for t, find k.<BR>\n" );
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document.write( "R(t)=600/&#12310;1+75e&#12311;^24k<BR>\n" );
document.write( "40-600/&#12310;1=75e&#12311;^24k <BR>\n" );
document.write( "(40-600/&#12310;1)/(75&#12311;)=e^24k<BR>\n" );
document.write( "ln((40-600/&#12310;1)/(75&#12311;))=ln(e^24k)<BR>\n" );
document.write( "ln((40-600/&#12310;1)/(75&#12311;))=24k<BR>\n" );
document.write( "(ln((40-600/&#12310;1)/(75&#12311;)))/24=k<BR>\n" );
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document.write( "Then using (0.90)(600)=540 for R(t) and the  value of k from above, solve for t.<BR>\n" );
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document.write( "If you can clarify your equation, I can offer more help.<BR>\n" );
document.write( "I noticed you re-posted the same garbled equation again, perhaps someone else can help you. </SPAN>\n" );
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