Problem 3.2 (10 points) Let $(S_n)_{n \ge 0}$ be the symmetric simple random walk starting in 0 (i.e. $S_0 = 0$) with $p = 0.5$.
Compute explicitly the following probabilities:
(a) (3 points) $\mathbb{P}_0(S_2 = -2|S_9 = -3)$;
(b) (3 points) $\mathbb{P}_0(S_2 \le 0, S_6 = 2, S_8 = 2)$;
(c) (4 points) $\mathbb{P}_0(T_2 \le 9)$, where $T_k := \min\{n > 0 : S_n = k\}$.