keeping in mind that the diameter is twice as long as the radius, then
[tex]\bf \textit{volume of a cylinder}\\\\
V=\pi r^2 h~~
\begin{cases}
r=radius\\
h=height\\
-----\\
V=1318.8\\
h=15
\end{cases}\implies 1318.8=\pi r^2(15)\implies \cfrac{1318.8}{15\pi }=r^2
\\\\\\
\cfrac{87.92}{\pi }=r^2\implies \sqrt{\cfrac{87.92}{\pi }}=r\qquad \qquad \qquad\qquad\stackrel{\textit{so the diameter is}}{2\sqrt{\cfrac{87.92}{\pi }}}[/tex]
