$A$ 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..........$\pi\, m^2$.

The curved surface area of a circular cylinder of height $h$ and the slant surface area of a cone of slant height $2h$,having the same circular base,are in the ratio of:

The height and base radius of a cone are each increased by $100 \%$. The volume of the cone now becomes

The radius of the base of a conical tent is $5 \, m$. If the tent is $12 \, m$ high,then the area of the canvas required to make the tent is (in $\pi \, m^2$)

$A$ cylinder and a cone have their heights in the ratio $2:3$ and the radii of their bases in the ratio $3:4$. Find the ratio of their volumes.

$A$ cylindrical jar of diameter $24\, cm$ contains water to a height of $30\, cm$. $A$ spherical steel ball is dropped into the jar and the level of the water rises by $67.5\, mm$. The diameter of the ball is......$cm$.