the "cylinder" has a diameter of 6, and therefore its radius is half that, or 3, thus
[tex]\bf \textit{volume of a cylinder}\\\\
V=\pi r^2 h~~
\begin{cases}
r=radius\\
h=height\\
-----\\
r=3\\
h=11
\end{cases}\implies V=\pi (3)^2(11)\implies V=99\pi [/tex]