$A$ right circular cylindrical tunnel of diameter $5\, m$ and length $10\, m$ is to be constructed from a sheet of iron. The area of iron sheet required will be..........$\pi\, m^2$.

If a solid cone of volume $27\, \pi\, cm^3$ is kept inside a hollow cylinder whose radius and height are the same as that of the cone,then the volume of water needed to fill the empty space is...........$\pi\, cm^3$.

$A$ prism with a right triangular base is $25\, cm$ high. If the shorter sides of the triangle are in the ratio of $1: 2$ and the volume of the prism is $100\, cm^3$, what is the length of the longest side of the triangle?

The circumference of the base of a $9\, m$ high conical tent is $44\, m$. The volume of the air contained in it is.........$m^3$

If a sphere of radius $r$ is divided into $4$ identical parts,then the total surface area of the $4$ parts is

$A$ solid cylinder has a total surface area of $231 \, cm^2$. Its curved surface area is $(2/3)$ of the total surface area. Find the volume of the cylinder (in $cm^3$).