On the inside of a wall, there is a 1 cm thick plaster with a thermal conductivity of 1.3 
. It is followed by a 40 cm thick brick with a thermal conductivity of 0.8 and then on the outside is a 4 cm thick plaster with a thermal conductivity of 0.6 . Calculate the thermal resistance of a square metre of the wall. At what temperature difference does the wall have a heat flow rate of 30 W through a square metre of the wall?
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