Question

Find the radius of a hemisphere with the volume of $20$ cm${}^3$. $(\pi =3.142)$

• A. $2.121\text{cm}$
• B. $4.121\text{cm}$
• C. $5.121\text{cm}$
• D. None of these

Answer 1

Answer: (A)

$2.121\text{cm}$

Volume of hemisphere is $V=\frac{2}{3}\pi r^3$

$\Rightarrow r={\left(\frac{3V}{2\pi }\right)}^{\frac{1}{3}}$

$\Rightarrow r={\left(\frac{3\times 20}{2\pi }\right)}^{\frac{1}{3}}$

$\Rightarrow r=2.121\text{cm}$