Find the amount of water displaced by a solid spherical ball of diameter $4.2 \, cm$,when it is completely immersed in water. (in $, cm^3$)

The diameter of the moon is approximately one-fourth of the diameter of the earth. What fraction of the volume of the earth is the volume of the moon?

The water for a factory is stored in a hemispherical tank whose internal diameter is $14\, m$. The tank contains $50$ kilolitres of water. Water is pumped into the tank to fill it to its capacity. Calculate the volume of water pumped into the tank. (in $, m^{3}$)

$A$ capsule of medicine is in the shape of a sphere of diameter $3.5 \, mm$. How much medicine (in $mm^3$) is needed to fill this capsule (in $, mm^3$)?

Twenty-seven solid iron spheres,each of radius $r$ and surface area $S$,are melted to form a single sphere with surface area $S'$. Find the ratio of $S$ to $S'$.

Find the volume of a sphere of radius $2.1 \, cm$. (in $cm^3$)