A mixture consisting of 60% ice and 40% water by volume is filled in a thin-walled spherical vessel. The diameter of the spherical container is 30cm, and it is placed in a room where the air is at 20C. The temperature of the ice/water mixture is 0C. Given density of ice is 916.7 kg/m3 and heat of fusion of ice is 333.6kJ/kg. Estimate how long will it take for all the ice to melt (in hours). Ignore the radiation effects