Answer
$$2.3 \times 10^{3} \mathrm{\ m}$$
Work Step by Step
For silver $k_{s}=428 \mathrm{W} / \mathrm{m} \cdot \mathrm{K},$ so
$$L_{s}=k_{s} R_{s}=\left(\frac{k_{s} R_{s}}{k_{p} R_{p}}\right) L_{p}=\left[\frac{428(30)}{0.024(30)}\right](0.13 \mathrm{m})=2.3 \times 10^{3} \mathrm{\ m}$$
