A closed box is filled with dry ice at a temperature of -88.7 oC, while the outside temperature is 24.4 oC. The box is cubical, measuring 0.354 m on a side, and the thickness of the walls is 3.88 × 10-2 m. In one day, 3.73 × 106 J of heat is conducted through the six walls. Find the thermal conductivity of the material from which the box is made.