Chapter 3.1, Problem 56E

SAT Scores by Income The following bar graph shows U.S. critical reading SAT scores as a function of household income:⁹

These data can be modeled by

$S\left(x\right)=550-136{\left(0.985\right)}^x,$ where $S\left(x\right)$ is the average critical reading SAT score of students whose household income is x thousand dollar per year. Numerically estimate ${\lim }_{x\to +\infty }S\left(x\right),$ and interpret the answer.