Find the volume and surface area of a sphere whose radius is:

Solution:

(i) Radius of the sphere = 3.5 cm

Now, volume $=\frac{4}{2} \pi r^{3}$

$=\frac{4}{3} \times \frac{22}{7} \times 3.5 \times 3.5 \times 3.5$

$=179.67 \mathrm{~cm}^{3}$

$\therefore$ Surface area $=4 \pi r^{2}$

$=4 \times \frac{22}{7} \times 3.5 \times 3.5$

$=154 \mathrm{~cm}^{2}$

(ii) Radius of the sphere=4.2 cm

Now, volume $=\frac{4}{3} \pi r^{3}$

$=\frac{4}{3} \times \frac{22}{7} \times 4.2 \times 4.2 \times 4.2$

$=310.46 \mathrm{~cm}^{3}$

$\therefore$ Surface area $=4 \pi r^{2}$

$=4 \times \frac{22}{7} \times 4.2 \times 4.2$

$=221.76 \mathrm{~cm}^{2}$

(iii) Radius of sphere=5 m

Now, volume $=\frac{4}{3} \pi r^{3}$

$=\frac{4}{3} \times \frac{22}{7} \times 5^{3}$

$=523.81 \mathrm{~cm}^{3}$

$\therefore$ Surface area $=4 \pi r^{2}$

$=4 \times \frac{22}{7} \times 5^{2}$

$=314.29 \mathrm{~cm}^{2}$