If the odds against is 2/7, what is the probability the event WILL occur?

Answer 1

Think of odds against as a ratio of the number of times the event does not happen compared to the number of times it does. So 2/7 or 2:7 odds against means for every 2 occurrences that it doesn't happen, there will be 7 occurrences that it does happen. This means you will have a the event occurring a total of 2 out of every 9 (2+7) times. So your probability is 2/9 or approximately 0.222.