A spherical liquid metal droplet of diameter 1 mm is solidified in a stream of gas at 300 K. Assuming that the metal droplet remains at its melting point of 900 K and neglecting radiative losses, the time to complete the solidification is ______ (in seconds to one decimal place).

Given: The enthalpy of fusion for the metal is 4000 kJ kg^-1; The gas-droplet convective heat transfer coefficient is 200 W m^-2 K^-1; Density of liquid metal is 2700 kg m^-3.