radius : 3.95 ft
[tex]\sf volume \ of \ cone: \dfrac{1}{3} \pi r^2h[/tex]
[tex]\hookrightarrow \sf \dfrac{1}{3} \pi r^2(9) = 147[/tex]
[tex]\hookrightarrow \sf r^2 = \dfrac{147*3}{\pi (9)}[/tex]
[tex]\hookrightarrow \sf r = \sqrt{\dfrac{147*3}{\pi (9)}}[/tex]
[tex]\hookrightarrow \sf r = 3.95 \ ft[/tex]