same here, the diameter is 3.5, so its radius is half that, 1.75.
[tex]\bf \textit{volume of a cylinder}\\\\ V=\pi r^2 h~~ \begin{cases} r=radius\\ h=height\\[-0.5em] \hrulefill\\ r=1.75\\ h=12 \end{cases}\implies V=\pi (1.75)^2(12) \\\\\\ V=36.75\pi \implies \stackrel{using~\pi =3.14}{V\approx 115.40}[/tex]
