The probability that an event will not happen is Upper P left parenthesis Upper E prime right parenthesis PE′ equals = 0.77 0.77. Find the probability that the event will happen.

Question

The probability that an event will not happen is

Upper P left parenthesis Upper E prime right parenthesisPE′equals=0.770.77.

Find the probability that the event will happen.

Answer 1

If P(E') = 0.77, then P(E) = .23.

The sum of the probabilities of all outcomes of an event must add up to 1. For any event E, the only two outcomes are that either event A occurs, or event A does not occur. So, P(E) + P(E') = 1.

We call E' the complement of E, and P(E') is typically found by evaluating 1 - P(E). The same goes for finding P(E) when P(E') is known.