2) (Spt) Consider the zombie apocalypse where the probability that before night, you survive tomorrow is 0.8, and the probability that you turn into a zombie is 0.2, and during the night the survival probability is 0.6 and the probability that you turn into a zombie is 0.4. Then, what is the expectation of the survived days? (Hint: you survive a single day, only if you survive for both the day and the night)