🎲Probability Calculator
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.
- 1P(A) = favourable / total equally likely outcomes
- 2P(A) + P(not A) = 1
- 3P(A and B) = P(A) × P(B) for independent events
- 4P(A or B) = P(A) + P(B) − P(A and B)
Drawing an ace from a standard deck=P = 4/52 ≈ 7.7% · Odds 1:124 aces out of 52 cards
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Fun Fact
The gambler's fallacy — believing past outcomes affect future independent events — is one of the most pervasive cognitive biases. Each coin flip is always 50/50 regardless of history.
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