SOLUTION: If the formula R=-0.037x + 50.1 can be used to predict the world record in the 400-meter dash x years after 1925, for what years will the world records be 48.6 seconds or less?

Question 186403: If the formula R=-0.037x + 50.1 can be used to predict the world record in the 400-meter dash x years after 1925, for what years will the world records be 48.6 seconds or less?
Answer by ankor@dixie-net.com(22740) (Show Source): You can put this solution on YOUR website!
If the formula R =-0.037x + 50.1 can be used to predict the world record in the
400-meter dash x years after 1925, for what years will the world records be
48.6 seconds or less?
;
replace R with 48.6 and find x
:
-0.037x + 50.1 =< 48.6
:
-.037x =< 48.6 - 50.1
:
-.037x =< - 2.1
:
.037x => 2.1; multiplied equation by -1, this reverses the inequality sign
x =>
x => 56.8 ~ 57 yrs from 1925
:
1925 + 57 = 1982 and thereafter

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