Answer:
Here is a tree diagram representing the sample space of the compound event of selecting one tile from each container:
```
Bag
/ | \
X Y Z
/ \ / \ / \
1 2 1 2 1 2
```
The first level of the tree represents the selection from the bag, and the second level represents the selection from the box. There are three branches at the first level, one for each letter tile in the bag, and two branches at the second level, one for each number in the box. The sample space consists of all possible combinations of one tile from the bag and one tile from the box.