Question

Find the volume of a sphere, if its surface area is 154 sq.cm.

Answer 1

Let the radius of the sphere be r cm.

Surface area of the sphere = 154 cm²

∴ 4$\mathrm{\pi }$r² = 154 cm²

$$\begin{gathered} \Rightarrow 4\times \frac{22}{7}\times r^2=154 \\ \Rightarrow r^2=\frac{154\times 7}{88}=12.25 \\ \Rightarrow r^2={\left(3.5\right)}^2 \\ \Rightarrow r=3.5\mathrm{cm} \end{gathered}$$
∴ Volume of the sphere = $\frac{4}{3}\mathrm{\pi }{r}^3=\frac{4}{3}\times \frac{22}{7}\times {\left(3.5\right)}^3$ = 179.67 cm³

Thus, the volume of the sphere is 179.67 cm³.