The ratio of total surface area to lateral surface area of a cylinder whose radius is $80 \text{ cm}$ and height $20 \text{ cm}$ is: (in $:1$)

The radius of a cylinder is doubled and the height is halved. What is the ratio between the new volume and the previous volume?

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

$A$ hollow sphere of internal and external diameters $4\,cm$ and $8\,cm$ respectively is melted into a cone of base diameter $8\,cm$. The height of the cone is......$cm$.

$A$ rectangular sheet of area $264 \text{ cm}^2$ and width $11 \text{ cm}$ is rolled along its breadth to make a hollow cylinder. The volume of the cylinder is (in $\text{cm}^3$):

Find the length of the canvas $2 \ m$ in width required to make a conical tent $12 \ m$ in diameter and $6.3 \ m$ in slant height (in $m$).