The capacity of a cuboidal tank is $50000$ litres of water. Find the breadth of the tank,if its length and depth are respectively $2.5\, m$ and $10\, m$. (in $, m$)

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 curved surface area of a right circular cone whose slant height is $10\, cm$ and base radius is $7\, cm$. (in $, cm^{2}$)

Find the volume of a sphere whose radius is $7 \, cm$. Assume $\pi = \frac{22}{7}$.

$A$ 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 $\sqrt{1.04} = 1.02$)

$A$ 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 $,m^3$)