A small cube of hot aluminum ($m=500\text{ g}$; $T=300\ ^{ \circ }\text{C}$) is dropped in a $20\text{ kg}$ bucket of $15\ ^{ \circ}\text{C}$ water.

What is the final temperature of the contents in the bucket after equilibrium is reached?

The specific heat capacity of water is $4180$ $\frac { J }{ kg_{ }^{ \circ }{ C } }$ and the specific heat of aluminum is $900$ $\frac { J }{ kg_{ }^{ \circ }{ C } }$.