Final answer:
To find the odds against event F, divide the probability of event F not occurring by the probability of event F occurring.
Step-by-step explanation:
To find the odds against event F, we need to calculate the probability of event F not occurring and divide it by the probability of event F occurring. Since the events e and f are independent, the probability of event F not occurring is 1 - p(F).
Odds against = (1 - p(F)) / p(F)
Substituting the given value of p(F) = 0.28:
Odds against = (1 - 0.28) / 0.28 = 0.72 / 0.28 = 2.57