A $0.40\ \text{kg}$ copper block at $95\ ^\circ\text{C}$ is dropped into $0.25\ \text{kg}$ of water at $20\ ^\circ\text{C}$. What is the final temperature, if no heat is lost? (Copper $385\ \text{J kg}^{-1}\text{K}^{-1}$, water $4186\ \text{J kg}^{-1}\text{K}^{-1}$.)