We determine first the real dimension of the circular fountain by using the scale factor given.
(18 cm) x (4 ft / 3 cm) = 24 ft
Then, calculate for the area of the base of the circular fountain by the equation,
A = πD²/4
where A is are and D is diameter. Substituting,
A = π(24 ft)²/4 = 144π ft² ≈ 452.4 ft²
Thus, the area of the base of the circular fountain is approximately 452.4 ft².