#### Answer

$18$

#### Work Step by Step

The average rate of change from $2$ to $4$ is given by $\frac{f(4)-f(2)}{4-2}$.
Thus, the average rate of change from $2$ to $4$ is:
$\dfrac{f(4)-f(2)}{4-2}\\$
$=\dfrac{3(4)^2-2 -(3(2)^2-2)}{2}\\$
$=\dfrac{36}{2}=18$