document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=874689>Question 874689</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Click here to see ALL problems on Miscellaneous Word Problems<BR>\n" );
document.write( "Question 874204: A city has been declining in population for the last 50 years. <BR>\n" );
document.write( "I have not learned the number e yet, or ln. The answer I was given to this question did not make sense to me. :(<BR>\n" );
document.write( "Please help me again! \r<BR>\n" );
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document.write( "In the year 2000, the population was 571 thousand, and was declining at a rate of 0.77% per year. If this trend continues: \r<BR>\n" );
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document.write( "(A) Give a formula for the population of this city, P, in thousands, as a function of t, the number of years since 2000. <BR>\n" );
document.write( "P= <BR>\n" );
document.write( "(B) What is the predicted population in 2010? <BR>\n" );
document.write( "The predicted population is thousand people. \r<BR>\n" );
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document.write( "(C) To two decimal places, estimate t when the population is 450 thousand people. <BR>\n" );
document.write( "When there are 450 thousand people in this city, t&#8776;  </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #527670 by </B><A HREF=/tutors/aboutme.mpl?userid=rothauserc><B>rothauserc(4718)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=rothauserc><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=rothauserc><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=527670\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> A) P(t) = P0*e^rt, where P(t) is population at time t, r is the rate, t is time in years<BR>\n" );
document.write( "B)r= -0.0077, t = 10, e = 2.71828<BR>\n" );
document.write( "P(10) = 571,000*e^(-0.0077)10<BR>\n" );
document.write( "P(10) = 528,683<BR>\n" );
document.write( "C)450000 = 571000*e^(-0.0077)t<BR>\n" );
document.write( "450000/571000 = e^(-0.0077)t<BR>\n" );
document.write( "0.7880 = e^(-0.0077)t<BR>\n" );
document.write( "(-0.0077)t = ln (0.7880)<BR>\n" );
document.write( "(-0.0077)t = &#8722;0.2383<BR>\n" );
document.write( "t = 30.95 years<BR>\n" );
document.write( "When there are 450 thousand people in this city, t&#8776; 30.95 years\r<BR>\n" );
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