Question

If the surface area of a sphere is $100\pi {\text{cm}}^2$, then its radius is equal to

• A. $25\text{cm}$
• B. $100\text{cm}$
• C. $5\text{cm}$
• D. $10\text{cm}$

Answer 1

The correct option is C $5\text{cm}$

The total surface area of a sphere is equal to $4\pi r^2$. It is given that surface area is equal to $100\pi c{m}^2$

Hence. on equating these two information,

$\begin{array}{cc}4\pi r^2& =100\pi \\ r^2& =25\\ r& =5\text{cm}\end{array}$

Hence, option $C$ is the correct answer.