Mathematics for IGCSE & O level - Probability (Section 6 - No. 26)

If the probability of an event is 0.7, what are the odds *against* that event happening?

7:3

3:7

7:10

3:10

If the probability is 0.7 (70%), then the probability of not happening is 0.3 (30%). The odds against are 3:7 (3 unfavorable to 7 favorable).