This just does not make sense.
a 3x3x3 ft^3=27ft^3
it cannot be circular case if it is a cube
if a water tank is 3feet*3feet*3feet how much water it will contain and if it is circular case and diameter is of 5feet n height 5feet
2 answers
maybe they're separate problems. In that case, just use the normal formula
v = π/4 d^2 h
and use your numbers
v = π/4 d^2 h
and use your numbers