<PRE><B>Question 179348</B>
from 1920-1960 there is 40 years
:
the difference between 45.4-44.6=.8
:
that difference took place over a 40 year span so we have to divide the difference by 40 to get a yearly average of the change
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.8/40=.02.  this is how much on average per year that the race time is falling
:
equation: R(t)=-.02t+45.4
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b)2003 would be 83 years:R(83)=-.02(83)+45.4=-1.66+45.4=43.74sec
  2006 would be 86 years:R(86)=-.02(86)+45.4=-1.72+45.4=43.68sec
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c)43.4=-.02t+45.4
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-.02t=-2
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t=100 years......so in the year 2020 this formula predicts a time of 43.4sec</PRE>