Answer
12 inches.
Step-by-step explanation
A cone is a shape whose volume is equal to a third of the cylinder with that same base area and the save vertical height.
With such definition, we can say that the volume of a cone is a third the volume of a cylinder.
CB is the radius and is equal to 6 in.
Diameter is usually twice the radius.
∴ Diameter = 2 × 6 = 12 inches.