The moment of inertia of solid sphere is defined as, the moment of inertia is equal to the product of mass and radius. Here, football and stone as a solid sphere.
I = MR2
We need to calculate the moment of inertia of football
Using formula of moment of inertia of a solid sphere
I = 2/3MR2
Put the value into the formula I = 2/3mr2
If a football and a stone has same mass then the moment of inertia will be same.
Hence, both have same inertia