assuming the silo is a right-circular cylinder.
since its diameter is 11.1, its radius is half that, namely 5.55.
[tex]\bf \textit{volume of a cylinder}\\\\ V=\pi r^2 h~~ \begin{cases} r=radius\\ h=height\\[-0.5em] \hrulefill\\ r=5.55\\ h=20 \end{cases}\implies V=\pi (5.55)^2(20)\implies V=616.05\pi[/tex]
