document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=135865>Question 135865</A>: <I><SPAN STYLE=\"word-break: break-all;\"> In 1920, the record for a certain race was 45.5 sec. In 1950, it was 45.2 sec. Let <BR>\n" );
document.write( "R(t)=the record in the race and t=the number of years since 1920.\r<BR>\n" );
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document.write( "a) Find a linear function that fits the data.<BR>\n" );
document.write( "b) Use the function in (a) to predict the record in 2003 and in 2006.<BR>\n" );
document.write( "c) Find the year when the record will be 44.6 sec.<BR>\n" );
document.write( "Find a linear function that fits the data.<BR>\n" );
document.write( "R(t)=?\r<BR>\n" );
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document.write( "Can you please help me with this? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #99529 by </B><A HREF=/tutors/aboutme.mpl?userid=solver91311><B>solver91311(24713)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=solver91311><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=solver91311><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=99529\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> The first key is that t must be the number of years since 1920, so 1920 represents year 0, and 1950 represents year 30.\r<BR>\n" );
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document.write( "Now you have two data points\r<BR>\n" );
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document.write( "t = 0, R(t) = 45.5<BR>\n" );
document.write( "t = 30, R(t) = 45.2\r<BR>\n" );
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document.write( "Therefore, you can plot two points on your graph:  (0,45.5) and (30,45.2)\r<BR>\n" );
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document.write( "Use the two-point form of a line to derive the equation that passes through the two points.  <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=y-y%5B1%5D=%28%28y%5B1%5D-y%5B2%5D%29%2F%28x%5B1%5D-x%5B2%5D%29%29%28x-x%5B2%5D%29 ALIGN=MIDDLE  ALT=\"y-y%5B1%5D=%28%28y%5B1%5D-y%5B2%5D%29%2F%28x%5B1%5D-x%5B2%5D%29%29%28x-x%5B2%5D%29\"   DISABLED_style= \"max-width:90%; height:auto;\" >\r<BR>\n" );
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document.write( " </SPAN>\n" );
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