Final answer:
The volume of a square pyramid varies jointly with the height and the square of the side length of the base. If the height is doubled and the side length of the base is tripled, the volume of the pyramid will change by a factor of 18.
Step-by-step explanation:
The volume, V, of a square pyramid varies jointly with the height, h, and the square of the side length of the base, s. This means that the volume is directly proportional to the height and the square of the side length of the base. So, if the height is doubled and the side length of the base is tripled, the volume of the pyramid will change by a factor of:
2*3² = 18