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?
;
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 => {{{2.1/.037}}}
x => 56.8 ~ 57 yrs from 1925
:
1925 + 57 = 1982 and thereafter