Final answer:
The fountain has a volume of 5184 cubic feet.
Step-by-step explanation:
The fountain can be represented as four squares, each with a side length of 12 feet. Since it is 3 feet deep, the volume of the fountain can be calculated by finding the volume of one of the squares and then multiplying it by 3. The formula for the volume of a cube is side length cubed, so the volume of one square is 12^3 = 1728 cubic feet. Therefore, the volume of the fountain is 1728 cubic feet x 3 = 5184 cubic feet.