Probability
AND means multiply, OR means add (if they can't both happen).
Mutually exclusive eventsIndependent eventsTree diagramsRelative frequency
📖 Learn
Sum to 1
P(not A) = 1 − P(A).
Independent
P(A and B) = P(A) × P(B). Two heads: ½ × ½ = ¼.
Relative frequency
Experimental probability = times it happened ÷ number of trials.
Worked example
P(six then six) with a fair dice
- 1P(six) = 1/6
- 2Independent → multiply
- 31/6 × 1/6 = 1/36 ✅
🧪 Play with it: Dice roller
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0 rolls · relative frequency of a 6: – (theory: 0.167)
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