The volume of a hemisphere is equal to:

$A$ cylinder with radius $21 \, cm$ and height $18 \, cm$ is closed at both the ends by hemispheres. Find the surface area of this article. $(\pi = \frac{22}{7})$ (in $cm^2$)

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

The base of a cone is in the shape of a ..............

$1\,m^3 = \dots \dots \dots cm^3$.

The volume of a cylinder is given by: