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 $\pi =\frac{22}{7}$]

A metal pipe is $77 \mathrm{cm}$ long. The inner diameter of a cross-section is $4 \mathrm{cm}$, the outer diameter being $4.8 \mathrm{cm}$. Find its 

inner curved surface area

A metal pipe is $77 \mathrm{cm}$ long. The inner diameter of a cross-section is $4 \mathrm{cm}$, the outer diameter being $4.8 \mathrm{cm}$. Find its 

outer curved surface area

cA metal pipe is $77 \mathrm{cm}$ long. The inner diameter of a cross-section is $4 \mathrm{cm}$, the outer diameter being $4.8 \mathrm{cm}$. Find its 

total surface area