Find the volume of a cylinder, if the diameter (d) of its base and its altitude (h) are:

(i) Given :

$d=21 \mathrm{~cm}$, radius, $r=\frac{d}{2}=10.5 \mathrm{~cm}$

height, $h=10 \mathrm{~cm}$

Volume of the cylinder, $V=\pi r^{2} h$

$=\frac{22}{7} \times(10.5)^{2} \times 10$

$=3465 \mathrm{~cm}^{3}$

(ii) Given :

$d=7 \mathrm{~m}$, radius, $r=\frac{d}{2}=3.5 \mathrm{~m}$

height $h=24 \mathrm{~m}$

Volume of the cylinder, $\mathrm{V}=\pi r^{2} h$

$=\frac{22}{7} \times(3.5)^{2} \times 24$

$=924 \mathrm{~m}^{3}$