In places with very cold weather, it is recommended to wear several pieces of clothing one on top of the other, since layers of still air are formed between the different pieces of clothing and thus energy loss is reduced. Compare, by means of a quotient, the rate of heat transfer for the following possibilities: a) a person who uses a single wool garment (kL= 0.038 W/m*K) of 18 mm thickness; b) the same person wears three wool garments, each 6 mm thick, separated by air spaces 1.5 mm thick (ka=0.0237 W/m*K).