At (r_2 = r_cr = 0.00667 , m): ( R_total = \frac\ln(r_2/r_1)2\pi k L + \frac1h 2\pi r_2 L ) ( R_cond = \frac\ln(0.00667/0.0015)2\pi \times 0.08 = \frac\ln(4.4467)0.50265 = \frac1.4920.50265 \approx 2.97 ) ( R_conv = \frac112 \times 2\pi \times 0.00667 = \frac10.5027 \approx 1.99 ) ( R_total = 4.96 , K/W )