document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=257686>Question 257686</A>: <I><SPAN STYLE=\"word-break: break-all;\"> In 1920, the record for a certain race was 45.4 sec. In 1990, it was 44.7 sec. Let R(t) = the record race and t = number of years since 1920.<BR>\n" );
document.write( "I have found the linear function that fits the dats which is R(t) = -0.0175 + 45.4 and found the predicted record for 2003 which is 43.95 and the predicted record for 2006 which is 43.9.<BR>\n" );
document.write( "The problem I am having is finding the year that 44.50 is the predicted record. Could someone please help me with this on how to figure In what year will the predicted record be 44.50?\r<BR>\n" );
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document.write( "Thank you so much\r<BR>\n" );
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document.write( "Freda </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #189607 by </B><A HREF=/tutors/aboutme.mpl?userid=ankor@dixie-net.com><B>ankor@dixie-net.com(22740)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=ankor@dixie-net.com><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=ankor@dixie-net.com><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=189607\">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. In 1990, it was 44.7 sec. Let R(t) = the record race and t = number of years since 1920.<BR>\n" );
document.write( "In what year will the predicted record be 44.50? <BR>\n" );
document.write( ":<BR>\n" );
document.write( "I think there is a slight inaccuracy in the equation you came up with<BR>\n" );
document.write( ":<BR>\n" );
document.write( "The slope: m = <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=%2844.7-45.4%29%2F%2870+-+0%29+ ALIGN=MIDDLE  ALT=\"%2844.7-45.4%29%2F%2870+-+0%29+\"   DISABLED_style= \"max-width:90%; height:auto;\" > = <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=%28-.7%29%2F70 ALIGN=MIDDLE  ALT=\"%28-.7%29%2F70\"   DISABLED_style= \"max-width:90%; height:auto;\" > = -.01<BR>\n" );
document.write( "The equation should be:<BR>\n" );
document.write( " f(t)= -.01t + 45.4; where t is the years from 1920<BR>\n" );
document.write( "then<BR>\n" );
document.write( "2003: t=83<BR>\n" );
document.write( "f(t) = -.01(83) + 45.4<BR>\n" );
document.write( "f(t) = 44.57<BR>\n" );
document.write( "and the same way:<BR>\n" );
document.write( "2006: t=86<BR>\n" );
document.write( "f(t) = 44.54<BR>\n" );
document.write( ":<BR>\n" );
document.write( "Find the year when it's 44.50; find t when f(t) = 44.5<BR>\n" );
document.write( "-.01t + 45.4 = 44.5<BR>\n" );
document.write( "-.01t = 44.5 - 45.4<BR>\n" );
document.write( "-.01t = -.9<BR>\n" );
document.write( "t = <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=%28-.9%29%2F%28-.01%29 ALIGN=MIDDLE  ALT=\"%28-.9%29%2F%28-.01%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "t = +90 yrs<BR>\n" );
document.write( ":<BR>\n" );
document.write( "1920 + 90 = 2010 the year for a record of 44.5 seconds </SPAN>\n" );
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