Probability of a second event occurring given that a first event has already happened. Requires that one of these events is a Dependent Event
This may lead to the sample space for the second event to be smaller or bigger than the sample space of the first event.
OR
P(A and B) = P(A|B) * P(B) = P(B|A) * P(A)
Event probability that are affected by other events is denoted with the Probability: P(A|B). In section: Given Probability
You require:
- P(A)
- P(B|A)
Example
1% of people in lost articles realized theyve been punked. 5% of all people are in lost articles. What are chances that a person at lost articles will realize they’ve been punked? P(A) = 5% P(B|A) = 1% P(A|B) = 0.2