Find the volume of a sphere whose surface area is $1256 \, cm^{2}$. (Use $\pi = 3.14$)

The length of a metal hollow cylinder is $70\, cm$. If the radius of the hollow inside it is $10\, cm$ and the metal thickness is $1\, cm$,find the difference between the areas of the outer and inner curved surfaces.

The radii of three metal spheres are $3 \,cm, 4 \,cm$ and $5 \,cm$ respectively. They are melted into a single solid sphere. Find the radius of the new solid sphere (in $cm$).

The volumes of two spheres are in the ratio $64: 27$. Find the ratio of their surface areas.

Find the curved surface area and the total surface area of a hemisphere with a radius of $14\, cm$.

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