There is a 60 percent chance that the event A will occur. If A does not occur, then there is a 10 percent chance that B will occur.
(a) What is the probability that at least one of the events A or B occurs?
(b) If A is the event that the democratic candidate wins the presidential election in 2012 and B is the event that there is a 6.2 or higher earthquake in Los Angeles sometime in 2013, what would you take as the probability that both A and B occur? What assumption are you making?