Answer:
Sphere B has 4 times more inertia than sphere A.
Explanation:
Inertia on a Solid sphere is given by:
[tex]I = 2/5*M*R^2[/tex]
For this problem:
ma = mb = M
Rb = 2*Ra
With these values:
[tex]Ia = 2/5*M*Ra^2[/tex]
[tex]Ib = 2/5*M*(2*Ra)^2 = 4* (2/5*M*Ra^2)[/tex]
As you can see, Ib = 4 * Ia.