Answer
$(B)$
Work Step by Step
The average rate of change of $f$ over the interval $[a, b]$ is given by:
Average rate of change of $f\displaystyle \ \ =\frac{f(b)-f(a)}{b-a}$
The units of the average rate of change of $f$ are units of $f(x)$ per unit of $x$.
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Over $[4,8]$, the average rate of change for $f$ was
$\displaystyle \approx\frac{1.18-1.15}{8-4}=\frac{0.3}{7}$
and for the regression line, about
$\displaystyle \frac{1.15-1.34}{10-3}=\frac{-0.19}{7}$
Thus, we choose $(B)$.
