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

It is required to make a closed cylindrical tank of height $1 \,m$ and base diameter $140 \,cm$ from a metal sheet. How many square metres of the sheet are required for the same (in $,m^2$)? Assume $\pi = \frac{22}{7}$.

Find the capacity in litres of a conical vessel with height $12 \,cm$ and slant height $13 \,cm$.

$A$ hemispherical bowl is made of steel,$0.25 \, cm$ thick. The inner radius of the bowl is $5 \, cm$. Find the outer curved surface area of the bowl. (in $, cm^2$)

$A$ dome of a building is in the form of a hemisphere. From inside,it was white-washed at the cost of $Rs. 4989.60$. If the cost of white-washing is $Rs. 20$ per square metre,find the volume of the air inside the dome. (in $, m^3$)

The slant height and base diameter of a conical tomb are $25 \, m$ and $14 \, m$ respectively. Find the cost of white-washing its curved surface at the rate of $Rs. 210$ per $100 \, m^2$.