document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=144527>Question 144527</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Lost again, this one seems like it is not even in the book for how to solve it.  Any help would be appreciated.\r<BR>\n" );
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document.write( "In 1920, the record for a certain race was 45.4 sec.  In 1960, it was 44.6.  Let 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 frunction 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 43.6 sec.  </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #105270 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=105270\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> In 1920, the record for a certain race was 45.4 sec.<BR>\n" );
document.write( "In 1960, it was 44.6. <BR>\n" );
document.write( "Let R(t)= the record in the race and t= the number of years since 1920.<BR>\n" );
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document.write( "a) Find a linear frunction that fits the data.<BR>\n" );
document.write( "You have two points relating years since 1920 and race records:<BR>\n" );
document.write( "The points are (0,45.4) and (40,44.6)<BR>\n" );
document.write( "slope = (44.6-45.4)/(40-0) = -0.02<BR>\n" );
document.write( "intercept = 45.4<BR>\n" );
document.write( "EQUATION: record = (-0.02)(years since 1920) + 45.4<BR>\n" );
document.write( "r = -0.02t + 45.4<BR>\n" );
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document.write( "b) Use the function in (a) to predict the record in 2003 and in 2006.<BR>\n" );
document.write( "r(2003) = -0.02(2003-1920) + 45.4<BR>\n" );
document.write( "r(2003) = -0.02(83) + 45.4 = 43.74<BR>\n" );
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document.write( "r(2006) = ?????<BR>\n" );
document.write( "I'll let you do this following the same pattern as above.<BR>\n" );
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document.write( "c) Find the year when the record will be 43.6 sec. <BR>\n" );
document.write( "43.6 = -0.02t + 45.4<BR>\n" );
document.write( "-0.02t = -1.8<BR>\n" );
document.write( "t = 90<BR>\n" );
document.write( "year = 1920+90 = 2010<BR>\n" );
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document.write( "Cheers,<BR>\n" );
document.write( "Stan H.<BR>\n" );
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