Given that, radius of spherical ball = 3 cm

We know that, Volume of the sphere =

So, its volume, v =

The spherical ball of radius 3 cm is melted and recast into three spherical balls.

Let the radius of the third ball be r.

Then, volume of third spherical ball =

Volume of first ball =

Volume of second ball =

The volume of the original spherical ball is equal to that of the total volumes of the three balls.

⇒ r = 2.5 cm

Thus, diameter = 5 cm