The volume of a sphere with diameter $10 \, cm$ is $\ldots \ldots \, cm^3$.

Find the number of metallic circular discs with $1.5\, cm$ base diameter and height $0.2\, cm$ that must be melted to form a right circular cylinder of height $10\, cm$ and diameter $4.5\, cm$.

$A$ cylinder with radius $8 \, cm$ and height $9 \, cm$ is surmounted by a cone of height $15 \, cm$. Find the total surface area and the volume of the combined solid.

The volume of a sphere is equal to $\ldots \ldots \ldots . .$

How many balls with diameter $1 \, cm$ can be produced by melting a metallic cylinder with radius $6 \, cm$ and height $4 \, cm$?

$A$ metallic cone with radius $5 \, cm$ and height $8 \, cm$ is melted and recast to produce identical balls with diameter $0.5 \, cm$. Find the number of balls produced.