Mixing of water

In an insulated container of negligible heat capacity $1.0\mathrm{kg}$ of water at $90{}^{\circ }\mathrm{C}$ and $1.0\mathrm{kg}$ of water at $10{}^{\circ }\mathrm{C}$ are mixed ($c=4186J/(\mathrm{kg}\cdot \mathrm{K})$). Compute the final temperature and the change in entropy of the universe.