document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=90069>Question 90069</A>: <I><SPAN STYLE=\"word-break: break-all;\"> I have never been good at word problems I am not sure how to solve or even write the equation to solve it.<BR>\n" );
document.write( "In 1975 the population of the Earth was approximately 4 billion and doubling every 35 years. The formula for the population P in year Y for this doubling rate is<BR>\n" );
document.write( "P (in billions)<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+250%2A2+%28y-1975%29%2F35+ ALIGN=MIDDLE  ALT=\"+250%2A2+%28y-1975%29%2F35+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "The U.S. population in 1990 was approximately 250 million, and the average growth<BR>\n" );
document.write( "rate for the past 30 years gives a doubling time of 66 years. The above formula for the<BR>\n" );
document.write( "United States then becomes<BR>\n" );
document.write( "P (in millions) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+250+%2A+2%28+y-1990%29%2F66+ ALIGN=MIDDLE  ALT=\"+250+%2A+2%28+y-1990%29%2F66+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "The question is : What will the population of the United States be in 2025 if this<BR>\n" );
document.write( "growth rate continues?  </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #65401 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=65401\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> The U.S. population in 1990 was approximately 250 million, and the average growth rate for the past 30 years gives a doubling time of 66 years. The above formula for theUnited States then becomes <BR>\n" );
document.write( "P (in millions) =[ 250 * 2^[( y-1990)/66]]<BR>\n" );
document.write( "The question is : What will the population of the United States be in 2025 if thisgrowth rate continues?<BR>\n" );
document.write( "-------------<BR>\n" );
document.write( "P(2025) = [250*2^[(2025-1990)/66]<BR>\n" );
document.write( "P(2025) = [250*2^(35/66)]<BR>\n" );
document.write( "P(2025) = [250*1.444232517]<BR>\n" );
document.write( "P(2025) = [361.058... million]<BR>\n" );
document.write( "==============<BR>\n" );
document.write( "Cheers,<BR>\n" );
document.write( "Stan H.  </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );