The dimensions of a building are $30 \mathrm{m} \mathrm{x} 20 \mathrm{m} \times 40 \mathrm{m}$. If the walls, floor and roof of this building are to be repaired, the contractor asks for $₹50$ per square metre. What will be the estimate of the contractor for this work?

The curved surface area of a cylinder is $1,000 {\mathrm{cm}}^2$ and the radius of its base is $21 \mathrm{cm}$. Find the total surface area of the cylinder.

(Take $\pi =\frac{22}{7}$)

It costs $₹2200$ to paint the inner curved surface of a cylindrical vessel $10 \mathrm{m}$ deep. If it is painted at the rate of $₹20$per square metre, find:

the inner curved surface area of the vessel

It costs $₹2200$ to paint the inner curved surface of a cylindrical vessel $10 \mathrm{m}$ deep. If it is painted at the rate of $₹20$ per square metre, find:

the radius of the base 

A cylindrical road roller is of length $2 \mathrm{m}$ and diameter $84 \mathrm{cm}$. Find the number of revolutions it has to make to cover an area of $7,920 {\mathrm{m}}^2$.

[Take $\pi =\frac{22}{7}$]