Each relay in the following circuits will close with probability 0.8. If all relays function independently, what is the probability that a current flows between A and B for the respective circuits?...

Each relay in the following circuits will close with probability 0.8. If all relays function independently, what is the probability that a current flows between A and B for the respective circuits? (The circuit in part (a) of the figure, which needs both of its relays to close, is called a series circuit. The circuit in part (b), which needs at least one of its relays to close, is called a parallel circuit.)