Answer
$$0.13 \mathrm{\ m} $$
Work Step by Step
From Table $18-6$ we find $k_{p}=0.024 \mathrm{W} / \mathrm{m} \cdot \mathrm{K},$ so
$$
\begin{aligned} L_{p} &=k_{p} R_{p} \\ &=(0.024 \mathrm{W} / \mathrm{m} \cdot \mathrm{K})\left(30 \mathrm{ft}^{2} \cdot \mathrm{F}^{\circ} \cdot \mathrm{h} / \mathrm{B} \mathrm{tu}\right)(1 \mathrm{m} / 3.281 \mathrm{ft})^{2}\left(5 \mathrm{C}^{\circ} / 9 \mathrm{F}^{\circ}\right) \\ & \quad\quad (3600 \mathrm{s} / \mathrm{h})(1 \mathrm{Btu} / 1055 \mathrm{J}) \\ &=0.13 \mathrm{m} \end{aligned}
$$
