to a height of h ft, the radius of the surface of the liquid is h/4 ft (as the
filled part of the cone is similar to the whole cone the radius to height ratio
is the same as that for the whole cone). So r=h/4, hence the volume:
V=(1/3) pi r^2 h = (1/3) pi (h/4)^2 h= (1/48) pi h^3.
yesNOTE: Since the radius is 4 feet, does it mean the diameter of the cone is 8 feet?