Answer
$\displaystyle \lim_{x\rightarrow+\infty}S(x)=550$
Students living in households with extremely high incomes have an average critical reading SAT score of $550.$
Work Step by Step
When $x\rightarrow+\infty,$
$e^{-0.0151x }$ has the form $k^{Big\ negative }= Small$,
so, $550-136e^{-0.0151x }\rightarrow(550$ - small) $\rightarrow 550.$
$\displaystyle \lim_{x\rightarrow+\infty}S(x)=550$
Students living in households with extremely high incomes have an average critical reading SAT score of $550.$
