Question

The volume of a hemi-sphere is 2425$\frac{1}{2}c{m}^3$. Find its curved surface area.

Answer 1

Given : Volume of hemisphere = 2425$\frac{1}{2}c{m}^3$ or 2425.5 $c{m}^3$
Volume of hemisphere = $\frac{2}{3}$ $\pi$ $r^3$
$\Rightarrow$2425.5 = $\frac{2}{3}$ $\times$ $\frac{22}{7}$ $\times$ $r^3$
$\Rightarrow$ r³ = $\frac{2425.5\times 3\times 7}{22\times 2}$
$\Rightarrow$ r³ = $\frac{50935.5}{44}$
$\Rightarrow$ r³ = 1157.625
$\Rightarrow$ r = 10.5 cm
Now,
Curved Surface Area of hemisphere = 2πr²
= $2\times \frac{22}{7}\times 10.5\times 10.5$
= 693 sq cm
CSA of hemisphere is 693 sq cm.