Probability Tree

Probability Tree

Directed and valued graph responding to these rules:

  • The sum of the values (probabilities) associated with the edges coming from the same vertex gives 1,
  • The probability of a path is the product of the probabilities associated with the edges that compose it,
  • The value of an edge that goes from vertex S1 to vertex Sis the conditional probability of the event Sknowing that the event S1 has already occurred.


Below, we used a probability tree to represent tossing a coin two times.

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