The probability that an event will not happen is P(E)=0.68. Find the probability that the event will happen. (Simplify your answer).

Answer 1

P(event happens) + P(event does not happen) = 1 as these are mutually exclusive outcomes and one or the other must occur.

Therefore P(event happens) = 1 - P(event does not happen) = 1 - 0.68 = .32

Answer 2

Hi Susan!

The rule needed to do this problem is the Complement Rule: P(not E)=1-P(E). We can cut through the potentially confusing notation because the Complement Rule basically says, given the probability of something happening, to find the probability of the opposite happening instead subtract the given probability from 1. Since the question is asking about the opposite situation from my given probability, I will simply do 1-0.68=0.32, and that will be the probability the event happens.