1. Probability Using Venn Diagrams
I.. Probability: how likely an event is to occur.
A) Probability =
B) Probability is written like this…
1) The probability of event A occurring is P(A).
2) The probability of event B occurring is P(B).
C) We can use Venn diagrams to help us find the
probability of P(A or B) and P(A and B).

2. Probability Using Venn Diagrams
II.. Probability Using Venn Diagrams.
A) The union or intersection of two events is called a compound event.
B) Venn Diagrams:
C) For any 2 events: P(A or B) = P(A) + P(B) – P(A and B)
1) If A and B have no intersection, then they are called
disjointed or mutually exclusive events.
2) P(A or B) = P(A) + P(B) – 0 = P(A) + P(B).

3. Probability Using Venn Diagrams
III.. Math with Probability Using Venn Diagrams.
A) Since P(A or B) = P(A) + P(B) – P(A and B)
If we know the P(A), P(B) and the total number of events
P(A or B) we can find the intersection P(A and B) by using the formula and plugging in the known values.
Example: 200 seniors. 150 are taking either Pre-Cal or College Prep Math. 90 are in Pre-Cal and 70 are in College Prep.