What I think is that drilling a hole does not reduce the [1] Volume of Sphere.

Yes it will increase the [2] density as [3] Surface area will be increased due to drilling of hole,

but the volume will remain same.

Am I right?

[1] The volume of a sphere can be reduced only by reducing its radius, as it remains a sphere.

In the puzzle, the drilled sphere

is no longer a sphere - it's like a bead that can be put on a string.

The drill removes some volume of material from the sphere.

The question asks what is the volume of the

remaining **portion** **of the sphere**.

[2] Mass removed is proportional to the volume removed, so density

**remains the same.**Density has nothing to do with the puzzle, which is purely geometric.

[3] Surface area does not necessarily increase.

It may actually

**decrease** if the sphere is originally large enough.