The addition rule of probability is:
Inference 1: If A 1, A2, …, An are incompatible with each other, then: P (A1+A2+...+An) = P (A1)+P (A2)+…+P (An).
Inference 2: Let A 1, A2, ..., A form a complete event group, then: P (A1+A2+...+An) =1.
Inference 3: if b contains a, then P (B-A) = P (B)-P (A).
Inference 4 (generalized addition formula): For any two events A and B, there is p (a ∪ b) = p (a)+p (b)-p (ab)?
Extended data:
Calculation rules of mathematical probability and calculation of conditional probability in senior high school;
Conditional probability: the probability of occurrence of A under the condition that event B is known, which is called conditional probability and recorded as: P(A|B).
Conditional probability calculation formula:
When P(A) >; 0，P(B|A)=P(AB)/P(A)
When P(B)>0, P(A|B)=P(AB)/P(B)
Multiplication formula
P(AB)=P(A)×P(B|A)=P(B)×P(A|B)
Promotion: P(ABC)=P(A)P(B|A)P(C|AB)
Total probability theorem
Suppose: If events A 1, A2, …, An are incompatible with each other, and A 1+A2+…+an = ω, then A 1, A2, …, an constitutes a complete event group.
The form of the total probability formula is as follows:
The above formula is called the total probability formula.
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