Conditional probability
Definition · Level 13 · Interview mechanics
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The probability of an event given what you have been told: list the outcomes consistent with the information, then count the ones that work.
Example
Two children, at least one a boy: BB, BG, GB remain; only BB is two boys → 1/3.
Where Tradecraft teaches it
Level 13 · Interview mechanics, in the lesson “Probability: counting, “at least one” and conditions”: Count equally likely outcomes, use the complement for “at least one”, and update on what you are told.
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