Two thermally insulated reservoirs each contain 2 kg of water at temperatures of 80 °C and 20 °C respectively. The two quantities of water are mixed in one of the containers without heat transfer to the surroundings and are allowed to reach equilibrium. Determine the find equilibrium temperature and find the change in entropy of the local universe in the mixing process. The specific heat water is 4.18 J g-1 K-1.