\begin{definition}[Definition:Average Value of Function]
Let $f$ be an integrable function on some closed interval $\closedint a b$.
The '''average value of $f$''' (or '''mean value of $f$''') on $\closedint a b$ is defined as:
:$\ds \frac 1 {b - a} \int_a^b \map f x \rd x$
\end{definition}