6. An exterior wall of a house may be approximated by a 0.1 m layer common brock (k = 0.7 W/m-K) followed by a 0.04 m layer of gypsum plaster (k = 0.48 W/m-K). What thickness of loosely packed rock wool insulation (k = 0.065 W/m-K) should be added to reduce heat loss (or gain) through the wall by 80%. KLA -0.1m LB LC -0.04m-x Common brick Gypsum plaster Rock wool