587
Explanation:
A lead cube of side
is used to make spherical pellets of diameter
.
As the volume of lead is conserved, the volume of raw material equals the volume of finished products.

Let us assume that
cubes are produced. Volume of a cube of side
is
. The volume of a sphere of diameter
is
.

n is rounded off to 587.
∴ 587 spherical pellets can be made.