An edge of a variable cube is increasing at the rate

Let $x$ be the side and $V$ be the volume of the cube at any time $t$. Then,

$V=x^{3}$

$\Rightarrow \frac{d V}{d t}=3 x^{2} \frac{d x}{d t}$

$\Rightarrow \frac{d V}{d t}=3 \times(10)^{2} \times 3$          $\left[\because x=10 \mathrm{~cm}\right.$ and $\left.\frac{d x}{d t}=3 \mathrm{~cm} / \mathrm{sec}\right]$

$\Rightarrow \frac{d V}{d t}=900 \mathrm{~cm}^{3} / \mathrm{sec}$