Scaling of the volume of a sphere

n / The big sphere has 125 times more volume than the little one.

In figure n, the larger sphere has a radius that is five times greater. How many times greater is its volume?

Correct solution #1: Volume scales like the third power of the linear size, so the larger sphere has a volume that is 125 times greater (5³ = 125).

Correct solution #2: The volume of a sphere is V = (4/3)πr³, so

Incorrect solution: The volume of a sphere is V = pr³, so

(The solution is incorrect because (5r₁)³ is not the same as 5r³ ₁.)