Answer
In the period $2002-2007$, daily oil production decreased 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 $[2,7]$ is
$\displaystyle \frac{f(7)-f(2)}{7-2}=\frac{3.2-3.3}{5}=\frac{-0.1}{5}=-0.02$ million barrels per year.
Or, $-20,000$ barrels per year.
In the period $2002-2007$, daily oil production decreased at an average rate of $20,000$ barrels per year.
