Law of Addition of Probability.

1.	Law of Addition of Probability.
Answer» A and B are any two events of a finite sample space U. The probability that at least one of the two events A and B will occur is called the law of addition of probability. This rule is written as under : P(A ∪ B) = P(A) + P(B) – P(A ∩ B) If A ∩ B = Φ, then law of addition of probability is written as under: P(A ∪ B) = P(A) + P(B) If A and B are mutually exclusive and exhaustive events, then P(A ∪ B) = P(A) + P(B) = 1. The law of addition of probability for three events A, B and C of a sample space is written as under: P(A ∪ B ∪ C) = P(A) + P(B) + P(C) – P(A ∩ B) – P(A ∩ C) – P(B ∩ C) + P(A ∩ B ∩ C) If A, B, C are mutually exclusive events, then P (A ∪ B ∪ C) = P(A) + P(B) + P(C). If A, B, C are mutually exclusive and exhaustive events, then P(A ∪ B ∪ C) = P(A) + P(B) + P(C) = 1.

Answer»

A and B are any two events of a finite sample space U. The probability that at least one of the two events A and B will occur is called the law of addition of probability. This rule is written as under :
P(A ∪ B) = P(A) + P(B) – P(A ∩ B)

If A ∩ B = Φ, then law of addition of probability is written as under:
P(A ∪ B) = P(A) + P(B)
If A and B are mutually exclusive and exhaustive events, then
P(A ∪ B) = P(A) + P(B) = 1.
The law of addition of probability for three events A, B and C of a sample space is written as under:
P(A ∪ B ∪ C) = P(A) + P(B) + P(C) – P(A ∩ B) – P(A ∩ C) – P(B ∩ C) + P(A ∩ B ∩ C)
If A, B, C are mutually exclusive events, then P (A ∪ B ∪ C) = P(A) + P(B) + P(C).
If A, B, C are mutually exclusive and exhaustive events, then
P(A ∪ B ∪ C) = P(A) + P(B) + P(C) = 1.

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Law of Addition of Probability.

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