Answer
In the period $2001-2006$, daily US oil imports from Mexico increased at an average rate of $20,000$ barrels per year.
Work Step by Step
The average rate of change of $f$ over the interval $[a, b]$ is given as:
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 $x$.
$a.$
Average rate of change of $f$ over $[1,6]$ is
$\displaystyle \frac{f(6)-f(1)}{6-1}=\frac{1.5-1.4}{5}=\frac{0.1}{5}=0.02$ million barrels per year.
Or, $20,000$ barrels per year.
In the period $2001-2006$, daily US oil imports from Mexico increased at an average rate of $20,000$ barrels per year.
