The diameter of a metallic ball is $4.2\, cm$. What is the mass of the ball,if the density of the metal is $8.9\, g/cm^3$ (in $, g$)?

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

Find the amount of water displaced by a solid spherical ball of diameter $28 \, cm$.

$A$ small indoor greenhouse (herbarium) is made entirely of glass panes (including base) held together with tape. It is $30 \, cm$ long,$25 \, cm$ wide and $25 \, cm$ high. What is the area of the glass (in $, cm^2$)?

$A$ bus stop is barricaded from the remaining part of the road by using $50$ hollow cones made of recycled cardboard. Each cone has a base diameter of $40 \, cm$ and height $1 \, m$. If the outer side of each of the cones is to be painted and the cost of painting is $Rs. 12$ per $m^2$,what will be the cost of painting all these cones? (Use $\pi = 3.14$ and take $\sqrt{1.04} = 1.02$)

The circumference of the base of a cylindrical vessel is $132 \,cm$ and its height is $25 \,cm$. How many litres of water can it hold (in $,l$)? $(1000 \,cm^3 = 1 \,l)$ Assume $\pi = \frac{22}{7}$.