The volume of a cone with radius $6 \, cm$ and height $21 \, cm$ is $\ldots \ldots \ldots \, cm^{3}$.

The base of a cone with radius $0.6 \ m$ and height $1.6 \ m$ is hemispherical. Find the volume of this combined solid in $m^{3}$.

$A$ cylindrical bucket,$32 \, cm$ high and with a base radius of $18 \, cm$,is filled with sand. This bucket is emptied on the ground and a conical heap of sand is formed. If the height of the conical heap is $24 \, cm$,find the radius and slant height of the heap. [Take $\pi = \frac{22}{7}$]

The volume of a frustum of a cone is equal to $\ldots \ldots \ldots . .$

The volume of a sphere is $4.5 \pi \, cm^3$. Then,its diameter is $\ldots \ldots \ldots \ldots cm$.

The rainwater from a roof of dimensions $22 \, m \times 20 \, m$ drains into a cylindrical vessel having a base diameter of $2 \, m$ and a height of $3.5 \, m$. If the rainwater collected from the roof just fills the cylindrical vessel,find the rainfall in $cm$.