Answer
$a.\quad {{\$}} 60$ billion per year.
In the period 2005-2010, world military expenditure increased at an average rate of $ {{\$}} 60$ billion per year.
$b.\quad {{\$}} 50$ billion per year.
In the period 2000-2010, world military expenditure increased at an average rate of $ {{\$}} 50$ billion 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 ofthe average rate of change of $f$ are units of $f(x)$ per unit of $x$.
$a.$
Average rate of change of $f\ \ $ over $[5,10]$ is
$\displaystyle \frac{f(10)-f(5)}{10-5}=\frac{1600-1300}{10-5}=\frac{300}{5}=60$ billion per year.
In the period 2005-2010, world military expenditure increased at an average rate of $ {{\$}} 60$ billion per year.
$b.$
Average rate of change of $f\ \ $ over $[0,10]$ is
$\displaystyle \frac{f(10)-f(0)}{10-0}=\frac{1600-1100}{10-0}=\frac{500}{10}=50$ billion per year.
In the period 2000-2010, world military expenditure increased at an average rate of $ {{\$}} 50$ billion per year.
