Final answer:
The probability of the complement of event B is 1 minus the probability of event B. The complement of event B represents the set of all outcomes that are not in event B.
Step-by-step explanation:
The probability of the complement of an event B, denoted as B', is equal to 1 minus the probability of event B. In this case, if B is the event of a child having brown hair, then the probability of the complement of B is equal to 1 minus the probability of B. For example, if the probability of a child having brown hair is 0.7, then the probability of the complement of B (not having brown hair) is 1 - 0.7 = 0.3.
The complement of B represents the set of all outcomes that are not in event B. In this case, the complement of B represents the set of all children who do not have brown hair. It includes children with other hair colors like blond, black, or red.