## Thomas' Calculus 13th Edition

$\frac{2}{3}$
We calculate the average as: average=$\frac{1}{2\pi} \int^{2\pi}_0 \int^1_0 \int^1_{-1} 2r^2drd\theta$ =$\frac{1}{2\pi}\int^{2\pi}_0 \int^1_0 2r^2dr$ d $\theta$ =$\frac{1}{3\pi} \int^{2\pi}_0 d\theta$ =$\frac{2}{3}$