document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=744744>Question 744744</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Given: There are 7.3 billion, that is, 7.3*109<BR>\n" );
document.write( "people on Earth. If a flu virus starts<BR>\n" );
document.write( "with one person and within 1 day four more<BR>\n" );
document.write( "people are infected, then each of those four<BR>\n" );
document.write( "people in 1 day infects 4 people each, <BR>\n" );
document.write( "and so on, how many days before everyone<BR>\n" );
document.write( "on earth is infected? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #453524 by </B><A HREF=/tutors/aboutme.mpl?userid=tommyt3rd><B>tommyt3rd(5050)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=tommyt3rd><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=tommyt3rd><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=453524\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> This is an exponential growth problem where the population quadruples every day. Our model equation is:\r<BR>\n" );
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document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=P=P%5B0%5D%2A4%5Et ALIGN=MIDDLE  ALT=\"P=P%5B0%5D%2A4%5Et\"   DISABLED_style= \"max-width:90%; height:auto;\" >\r<BR>\n" );
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document.write( "with \r<BR>\n" );
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document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=P%5B0%5D=1 ALIGN=MIDDLE  ALT=\"P%5B0%5D=1\"   DISABLED_style= \"max-width:90%; height:auto;\" >, <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=P=7.3x10%5E9 ALIGN=MIDDLE  ALT=\"P=7.3x10%5E9\"   DISABLED_style= \"max-width:90%; height:auto;\" >\r<BR>\n" );
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document.write( "which leads to...\r<BR>\n" );
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document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=7300000000=4%5Et ALIGN=MIDDLE  ALT=\"7300000000=4%5Et\"   DISABLED_style= \"max-width:90%; height:auto;\" >\r<BR>\n" );
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document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=log7300000000=log+%284%5Et%29 ALIGN=MIDDLE  ALT=\"log7300000000=log+%284%5Et%29\"   DISABLED_style= \"max-width:90%; height:auto;\" >\r<BR>\n" );
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document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=t=%28log7300000000%29%2Flog4 ALIGN=MIDDLE  ALT=\"t=%28log7300000000%29%2Flog4\"   DISABLED_style= \"max-width:90%; height:auto;\" >\r<BR>\n" );
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document.write( "t is about...16.4 days </SPAN>\n" );
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