$A$ cone and a cylinder have equal radii and equal heights. Then,the ratio of their volumes is $\ldots \ldots \ldots . .$

The radius of a cone is $15 \, cm$ and its base is hemispherical. If the total height of the solid is $55 \, cm$,find its volume 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.

$A$ heap of rice is in the form of a cone of diameter $9 \, m$ and height $3.5 \, m$. Find the volume of the rice. How much canvas cloth is required to just cover the heap?

From a solid cube of side $7 \, cm$,a conical cavity of height $7 \, cm$ and radius $3 \, cm$ is hollowed out. Find the volume of the remaining solid (in $cm^3$).

$A$ rectangular water tank of base $11 \,m \times 6 \,m$ contains water up to a height of $5 \,m$. If the water in the tank is transferred to a cylindrical tank of radius $3.5 \,m$,find the height of the water level in the tank. (in $m$)