document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=880494>Question 880494</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Please help me set up an equation for this word problem! <BR>\n" );
document.write( " In 1994 , the National Park system consisted of about 74.9 million acres. By 2005, the figure had grown to 79 million acres. Let A (t) represent the amount of land in the National Park system, in millions of acres, t years after 1990. <BR>\n" );
document.write( "a) Find a linear equation that fits the data.<BR>\n" );
document.write( "b) Use the function of part (a) to predict the amount of land in the National Park system in 2010.<BR>\n" );
document.write( "Help on this problem would be greatly appreciated, thanks!! </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #531518 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=531518\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> a) we are given two data points (4, 74.9) and (15, 79)<BR>\n" );
document.write( "the slope(m) of the line is (79 - 74.9) / (15 - 4) = 0.372727273<BR>\n" );
document.write( "standard form of a line is y = mx + b, pick the first point<BR>\n" );
document.write( "74.9 = (0.372727273 * 4) + b<BR>\n" );
document.write( "74.9 = 1.490909091 + b<BR>\n" );
document.write( "b = 73.409090909<BR>\n" );
document.write( "A(t) = 0.372727273 * t + 73.409090909<BR>\n" );
document.write( "b) A(20) = 0.372727273 * 20 + 73.409090909<BR>\n" );
document.write( "A(20) = 80.863636369 million acres\r<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( " </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );