Question As shown in Figure 1, an ant crawls up from the bottom of the tree along the trunk. At each fork, the ant randomly chooses a path. What is the probability that it crawls to point $D$?
Because the ant choosing paths $H F, H G$ is equally likely, and after reaching point $G$, choosing paths $G D, G E$ is also equally likely, the probability of it reaching point $D$ is $\frac{1}{2} \times \frac{1}{2}=\frac{1}{4}$.

In fact, the probability of the ant reaching points $A, B, C$ is $\frac{1}{2} \times \frac{1}{3}=\frac{1}{6}$; the probability of the ant reaching points $D, E$ is $\frac{1}{2} \times \frac{1}{2}=\frac{1}{4}$.