If width of a hollow cylinder is $2 \mathrm{cm}$, its internal diameter is $14 \mathrm{cm}$ and height is $26 \mathrm{cm}$. Both the ends of cylinder are open. Assuming the total surface area of the hollow cylinder to be $k c{m}^2$, then find the value of $k$.

A solid metallic sphere of radius $6 cm$ is melted and made into a solid cylinder of height $32 cm$. Find the curved surface area of the cylinder. (Take $\pi =3.1$)

The diameter of a cylinder is $14 cm$ and its height is $10 cm$, then find the curved surface of the cylinder.

 A cylindrical tank with hemisphere ends having radius $0.42 m$ and total height $3.84 m$. Find total surface area of the closed tank.