Odds against
Odds against event = P(failure) ÷ P(success)
A ratio of the probability that the event will fail to occur (failure) to the probability the event will occur
Odds against if the outcomes are equally likely
Odds against event E = (number of outcomes unfavorable to E) ÷ (number of outcomes favorable to E)
Odds in favor of
Odds in favor of event = P(success) ÷ P(failure)
Expressed as a ratio of the probability that the event will fail to occur