An insulted storage tank contains $1000\:kg$ liquid of specific heat $10\:kJ\:kg^{-1}\:K^{-1}$. The liquid is heated by saturated steam, condensing in a helical coil at a temperature of $180 \:^{\circ}C$. The heat transfer area of the coil is $0.1\:m^{2}$. If the overall heat transfer coefficient is constant at $1000 \:W\:m^{-2}\:K^{-1}$, then the time (in hours) required to raise the temperature of the liquid in the tank from $20 \:^{\circ}C$ to $80 \:^{\circ}C$ is ________________ (rounded off to second decimal place).