Alaboratory furnace wall is constructed of 0.2 m thick fireclay brick having a thermal conductivity of 1.82 w/m-k. the wall is covered on the outer surface with insulation of thermal conductivity of 0.095 w/m-k. the furnace inner brick surface is at 950 k and the outer surface of the insulation material is at 300 k. the maximum allowable heat transfer rate through the wall of the furnace is 830 w/m^2. determine how thick in cm the insulation material must be.