Mathematics for IGCSE & O level - Probability (Section 4 - No. 22)

If the probability of an event occurring is 0.8, what are the odds against that event happening?

1:4

4:1

1:5

5:1

Odds against = (Probability of not happening) / (Probability of happening) = 0.2 / 0.8 = 1/4, 1:4.