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Probability of Event A OR Event B

Understanding the OR rule in probability is crucial for solving GRE problems, especially when dealing with mutually exclusive and non-mutually exclusive events.
  • The simple OR rule applies to mutually exclusive events, where the probability of A or B is the sum of their individual probabilities.
  • For non-mutually exclusive events, the general OR rule requires subtracting the overlap probability from the sum of the individual probabilities of A and B.
  • Visualizing these rules through diagrams can aid in comprehending why addition or subtraction is necessary in calculating probabilities.
  • The general OR rule, which accounts for overlap, is universally applicable and a powerful tool in probability calculations.
Introduction to the OR Rule
The Simple OR Rule for Mutually Exclusive Events
The General OR Rule for Non-Mutually Exclusive Events
Visualizing Probability with Diagrams