Alex bakes a total of $24$ pies, and each pie is apple, blueberry, or cherry. The ratio of apple to blueberry to cherry pies is $1:4:3$. How many cherry pies did Alex bake?
The $24$ pies are divided into $1+4+3 = 8$ equal parts. Thus, there are $\frac{24}{8} = 3$ pies per part. Since three parts of the pies are cherry, Alex baked $3 \cdot 3 = \boxed{9}$ cherry pies.