Question

what does the complement rule state?
a. $p(a) = p(a) \times + p(b)$
b. $p(a) = 1 - p(\text{not } a)$
c. $p(a) = p(a) \cdot p(b)$
d. $p(a) = p(a) - p(b)$

Explanation:

The complement rule in probability defines the probability of an event occurring as 1 minus the probability of the event not occurring. This is because the total probability of all possible outcomes (event A happening and event A not happening) equals 1.

Answer:

b. $P(A) = 1 - P(\text{not } A)$