Answer: The correct answer is 10 piranhas.
Explanation:
To calculate the total Volume of a cylinder we have to use the following formula:
Volume = Area * Height
Area = π * r² , where r= radius
The diameter is always the twice the radius so the diameter is 4 feet in this case and the radius is 2 feet so the area is
Area= 3.1416 * (2*2)
Area = 3.1416 * 4
Area = 12.5664 square feet
Volume = 12.5664 (area) * 1.25 (height).
Volume = 15.708 cubic feet
Each piranha needs 1.5 cubic feet so we have to divide the total Volume by the volume that each piranha needs
15.708/ 1.5 = 10.472 or ten pirahnas because we can't put a fraction of a piranha in the tank.