Answer
a) $14$
b) $18$
Work Step by Step
a) The average rate is given as: $\dfrac{f(b)-f(a)}{b-a}$ where $a \leq b$
$\dfrac{f(2013)-f(2003)}{2013-2003}=\dfrac{635-495}{10}=14$
b) Apply the rule such as
The average rate is given as: $\dfrac{f(b)-f(a)}{b-a}$ where $a \leq b$
$\dfrac{f(2004)-f(2003)}{20004-2003}=\dfrac{513-495}{1}=18$