SOLUTION: The equation R=-0.028t+20.8 can be used to predict the world record in the 200-m dash, where R is the record in seconds and t is the number of years since 1920. In what year will t

Question 620405: The equation R=-0.028t+20.8 can be used to predict the world record in the 200-m dash, where R is the record in seconds and t is the number of years since 1920. In what year will the record be 18.0 seconds?
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Answer by nerdybill(7384) (Show Source): You can put this solution on YOUR website!
The equation R=-0.028t+20.8 can be used to predict the world record in the 200-m dash, where R is the record in seconds and t is the number of years since 1920. In what year will the record be 18.0 seconds?
.
Set R to 18 and solve for t:
R=-0.028t+20.8
18=-0.028t+20.8
subtracting 20.8 from both sides:
-2.8=-0.028t
dividing both sides by -0.028:
-2.8/(-0.028) = t
100 = t
.
Since t is defined as "the number of years since 1920" we have:
1920+100 = 2020 (this is your answer)

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