If the edge of a cube is $7\, cm$,find its total surface area 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.

The curved surface area of a cylinder is $3960 \, cm^{2}$ and its volume is $41580 \, cm^{3}$. Find the radius and height of the cylinder.

Find the curved surface area of a cylinder whose height is $35 \, cm$ and radius of the base is $15 \, cm$. (in $cm^2$)

$A$ cuboidal water tank is $6 \,m$ long,$5 \,m$ wide and $4.5 \,m$ deep. How many litres of water can it hold (in $,l$)? $(1 \,m^3 = 1000 \,l)$

$A$ sphere and a right circular cylinder of the same radius have equal volumes. By what percentage does the diameter of the cylinder exceed its height?