If M and N are any two events, the probability that atleast one of them occurs is

If M and N are any two events, the probability that at least one of them occurs is

If M and N are any two events, then probability that at least one of them occurs is:

If M and N are any two events, the probability that exactly one of them occurs is (for an event set A, the complement is A^(@))

If M and N are any two events,then the probability that exactly one of them occurs is