An icebox almost comletely filled with ice at `0^(@)C` is dipped into a large volume of watert at `20^(@)C` . The box has walls of surface area `2400cm^(2)` thickness `2.0mm` and thermal conductivity 0.06Wm^(-1)`^(@)C^(-1)` . Calculate the rate at which the ice melts in the box. Letent heat of fusion of ice `=3.4xx10^(5)Jkg^(-1)` .