Question Video: Finding the Probability of the Complement of Events Mathematics • Third Year of Preparatory School

Video Transcript

Given that the probability of an event occurring is 0.87, what is the probability of the event not occurring?

The probability of an event occurring and the probability of it not occurring must add up to one. Probability of 𝐴 plus the probability of 𝐴 dash, its complement, must equal one.

In our example, the probability of the event occurring, 𝑃 of 𝐴, is equal to 0.87. This means that 0.87 plus the probability of the event not occurring equal one. Subtracting 0.87 from both sides of the equation gives us an answer that the probability of 𝐴 dash, the probability of the event not occurring, of 0.13.

If the probability of an event occurring is 0.87, then the probability of it not occurring is 0.13.