The volume of a $1-$ rupee coin is given by the formula $\ldots \ldots \ldots . . .$

Total surface area of a cylinder with radius $7 \, cm$ and height $13 \, cm$ is $\ldots \ldots \ldots \ldots \, cm^{2}$.

The base of a cone with radius $15 \, cm$ and slant height $25 \, cm$ is hemispherical. Find the volume of this solid. $(\pi = 3.14)$ (in $cm^3$)

The base of a cone is hemispherical. The radius of the cone is $15 \, cm$ and the total height of the solid is $55 \, cm$. Find the volume of this solid (in $cm^3$).

The base of a cone with radius $21 \, cm$ and height $20 \, cm$ is hemispherical. Find its curved surface area and volume.

Water is flowing at the rate of $15\, km/h$ through a pipe of diameter $14\, cm$ into a cuboidal pond which is $50\, m$ long and $44\, m$ wide. In what time will the level of water in the pond rise by $21\, cm$? (in $h$)