The odds against a certain event is 5 : 2 and the odds in favour of another is 6: 5 . If both the events are independent, then the probability that at least one of the events will happen is

The odds against a certain event is 5 : 2 and the odds in favour of another event is 6 : 5. If the both the events are independent, then the probability that at least one of the events will happen is

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

The odds against a husband who is 60 years old, living till he is 85 are 7:5 . The odds against his wife who is now 56, living till she is 81 are 5:3 . Find the probabilty that: at least one of them will be alive 25 years hence.