R = \dfrac{\rho L}{A} 이고, 부피 V_{\text{ol}} = A \cdot L 이므로 A = \dfrac{V_{\text{ol}}}{L} 입니다.

\displaystyle R = \dfrac{\rho L}{{V_{\text{ol/}}}{L}} = \dfrac{\rho L^{2}}{V_{\text{ol}}}

\displaystyle L^{2} = \dfrac{R \cdot V_{\text{ol}}}{\rho}

부피 V_{\text{ol}} = 10.0~\text{cm}^{3} = 1.0 \times 10^{-5}~\text{m}^{3} 입니다.

\displaystyle L^{2} = \dfrac{(5.0~\Omega) \times (1.0 \times 10^{-5}~\text{m}^{3})} {1.59 \times 10^{-8}~\Omega\cdot\text{m}} \approx 3145~\text{m}^{2}

\displaystyle L \approx \sqrt{3145~\text{m}^{2}} \approx 56~\text{m}