The smallest possible value for P(A ∪ B) is P(A) + P(B) - 1, and the largest possible value is 1.
To understand why, let's consider the probability of the union of two events, A and B. The probability of the union is given by P(A ∪ B) = P(A) + P(B) - P(A ∩ B), where P(A ∩ B) represents the probability of both events A and B occurring simultaneously.
Since probabilities are bounded between 0 and 1, the sum of P(A) and P(B) cannot exceed 1. If P(A) + P(B) exceeds 1, it means that the events A and B overlap to some extent, and the probability of their intersection, P(A ∩ B), is non-zero.
Therefore, the smallest possible value for P(A ∪ B) is P(A) + P(B) - 1, which occurs when P(A ∩ B) = 0. In this case, there is no overlap between A and B, and the union is simply the sum of their probabilities.
On the other hand, the largest possible value for P(A ∪ B) is 1, which occurs when the events A and B are mutually exclusive, meaning they have no elements in common.
If P(A) + P(B) > 1, the smallest possible value for P(A ∪ B) is P(A) + P(B) - 1, and the largest possible value is 1.
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