So,
The formula to find the volume of a cylinder is given by:
[tex]V=\pi\cdot r^2\cdot h[/tex]Where r is the radius and h is the height.
Replacing our values:
(0.8ft = 9.6in)
[tex]\begin{gathered} 9583in^3=\pi\cdot r^2\cdot9.6in \\ r^2=\frac{9583in^3}{9.6\pi in}\to r^2=317.7462in^2\to r=17.8254in \end{gathered}[/tex]The diameter is the double of the value of the radius. So,
[tex]D=2(17.8254)=35.7in[/tex]Therefore, the answer is 35.7in