From \( C(r) = \frac{40}{r} + 110\pi r^2 \), with \( r^3 = \frac{2}{11\pi} \Rightarrow r = \left( \frac{2}{11\pi} \right)^{1/3} \), \( r^2 = \left( \frac{2}{11\pi} \right)^{2/3} \)