An ice-ball of initial diameter 0.06m is suspended in a room at 30oC. The ice melts by absorbing heat from the ambient, the surface heat transfer coefficient being 11.4 W/m2 oC. The air in the room is essentially dry. If the shape of the ball remains unchanged, calculate the time required for reduction in its volume by 40%. The density of ice is 929 kg/m3 and its latent heat of fusion is 3.35 x 105 J/kg