A refrigerator converts 100 g of water at 20o C to ice at −10o C in 73.5 min. Calculate the average rate of heat extraction in watt. The specific heat capacity of water is 4.2 J g−1K−1, specific latent heat of ice is 336 J g−1 and the specific heat capacity of ice is 2.1 J g−1 K−1.