Find the surface area of a sphere with a diameter of $3.5 \, cm$. Assume $\pi = \frac{22}{7}$. (in $, cm^2$)

Find the surface area of a sphere of radius $5.6 \, cm$.
Assume $\pi = \frac{22}{7}$. (in $, cm^{2}$)

$A$ wooden bookshelf has external dimensions as follows: Height $= 110\, cm$,Depth $= 25\, cm$,Breadth $= 85\, cm$ (see Fig.). The thickness of the plank is $5\, cm$ everywhere. The external faces are to be polished and the inner faces are to be painted. If the rate of polishing is $20$ paise per $cm^2$ and the rate of painting is $10$ paise per $cm^2$,find the total expenses required for polishing and painting the surface of the bookshelf.

$A$ hemispherical tank is made up of an iron sheet $1 \,cm$ thick. If the inner radius is $1 \,m$,then find the volume of the iron used to make the tank. (in $,m^3$)

$A$ lead pencil consists of a cylinder of wood with a solid cylinder of graphite filled in the interior. The diameter of the pencil is $7 \,mm$ and the diameter of the graphite is $1 \,mm$. If the length of the pencil is $14 \,cm$,find the volume of the wood and that of the graphite. (in $,cm^3$)

$A$ right triangle $ABC$ with sides $5 \, cm, 12 \, cm$ and $13 \, cm$ is revolved about the side $12 \, cm$. Find the volume of the solid so obtained.