Thermodynamic entropy — UPSC Physics Optional CSE 2006 Paper I

1 kg of ice at 0^\circ\text{ C} floats on 10 kg of water at 30^\circ\text{ C}, the whole system being thermally isolated. What will be the change in entropy of the sytem when thermal equilibrium is reached ? [Specific heat of water = 4.2\text{ kJ kg}^{-1}\text{ K}^{-1} and latent heat of fusion of ice = 336\text{ kJ kg}^{-1}]