如何计算Probability

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Probability measures the likelihood of an event, from 0 (impossible) to 1 (certain). P = favourable outcomes / total outcomes. Odds express the same as favourable : unfavourable ratio.

分步指南

1. 1P(A) = favourable / total equally likely outcomes
2. 2P(A) + P(not A) = 1
3. 3P(A and B) = P(A) × P(B) for independent events
4. 4P(A or B) = P(A) + P(B) − P(A and B)

例题解析