We are not supposed to just give you the solutions to either the quiz questions or the programming assignments. Well, it’s been a couple of years (at least) since I listened to the lectures here, but this sounds like exactly the point of Bayes Theorem. You just have to be clear about what the definitions of the conditions A and B and A|B are and all that, right? Apply the ideas Younes explained in the lectures and I hope that will clarify things.