A school organized a competition of making and decorating pen holders in the shape of a cylinder by making its base and its curved surface area with cardboard. Each pen holder is supposed to have a radius of $3.5 \mathrm{cm}$ and height $10 \mathrm{cm}$. How much cardboard does the school need if $30$students are participating in the competition?

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