Answer:
452.4 ft²
Explanation:
The radius on the blueprint is (18 cm)/2 = 9 cm, so the actual radius will be ...
radius/(9 cm) = (4 ft)/(3 cm)
radius = (9 cm)(4 ft)/(3 cm) = 12 ft
Then the area of the fountain is ...
A = πr² = π(12 ft)² = 144π ft²
The area is about 452.4 ft².