If the amount of air in a spherical balloon is 288 pi cu. in.,

what is the radius of the balloon?

The balloon assumes the shape of a sphere with a formula of the volume equal to V = 4/3 pi r^3 where r is the radius of the balloon. In this case, we are given with volume of 288 pi in^3. We just substitute the given volume such that the resulting radius that answers the problem is 6 inches.