ANSWER
[tex]54ft^3[/tex]EXPLANATION
The volume of a cone is given by:
[tex]V=\frac{\pi r^2h}{3}[/tex]where r = radius
h = height
The height of the given cone is 6 ft and its diameter is 6 ft. The radius of a cone is half its diameter, hence its radius is:
[tex]\begin{gathered} r=\frac{6}{2} \\ r=3ft \end{gathered}[/tex]Hence, the volume of the cone is:
[tex]\begin{gathered} V=\frac{3\cdot3^2\cdot6}{3} \\ V=54ft^3 \end{gathered}[/tex]That is the answer.