A large insulator sphere of radius R has uniform charge distribution inside, and the total charge is Q. If you cut a small sphere of radius r from the the large sphere, The charge inside your small sphere is equal to:

The charge inside the small sphere is .

Explanation:

Since, charge is uniformly distributed throughout the sphere.

Therefore, charge density of sphere is,   .

Charge on sphere of radius r is,

Putting value of in above equation.

We get ,

Hence, this is the required solution.