Wearing layers of clothing in cold weather is often recommended because dead-air spaces between the layers help to keep the body warm. The explanation for this is that the heat loss from the body is less. Assume the temperature difference between the inner and outer surface of the clothing is a constant, compare the rate of heat loss for single layer of 2cm-thick wool and three layers of 0.67cm-thick wool separated by 1.5 mm air gaps (calculate the ratio between the two scenarios). The thermal conductivities of the wool and the air are 0.04 W/m/K and 0.024 W/m/K respectively.