Consider two long, slender rods of the same diameter but different materials. One end of each rod is attached to a base surface maintained at 100 C, while the surfaces of the rods are exposed to ambient air at 20 C. By traversing the length of each rod with a thermocouple, it was observed that the temperatures of the rods were equal at the positions xA 0.15 m and xB 0.075 m, where x is measured from the base surface. If the thermal conductivity of rod A is known to be kA 70 W/m K, determine the value of kB for rod B.