The given equation is
2/3 x pi x r^3
[tex]\begin{gathered} Multiply\text{ x }by\text{ 3 and divide by 2pi. we have} \\ \frac{3x}{2\pi}=\text{ }r^3 \\ \text{Taking the cube root of both sides of the equation, we have} \\ r\text{ = }\sqrt[3]{\frac{3x}{2\pi}} \end{gathered}[/tex]Thus, the correct option is C
