this is about the stochastic. I give some example for u, and please take a look,

this is about the stochastic. I give some example for u, and please take a look, if you think you are good at this, please tell me.
Then I will update the real question for u.
the time is for two hours. (I know I choices the 4 hours by this set, but unfortunately, I do not have enough time for u, so just try your best)
NOT: the example is not the question you need to answer!