Check the picture below.
since we know what its diameter is, well, its radius is half that.
[tex]\bf \textit{volume of a cone}\\\\ V=\cfrac{\pi r^2 h}{3}~~ \begin{cases} r=radius\\ h=height\\[-0.5em] \hrulefill\\ r=3.5\\ h=24 \end{cases}\implies V=\cfrac{\pi (3.5)^2(24)}{3}\implies V=98\pi \\\\\\ \stackrel{using~\pi =3.14}{V=307.72}\implies \stackrel{\textit{rounded up}}{V=307.7}[/tex]
