Chapter 10 Counting Methods and Probability - 10.4 Find Probabilities of Disjoint and Overlapping Events - 10.4 Exercises - Skill Practice - Page 711: 41

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We can see that there are 8 dots in A, 7 dots in B, 3 dots in A and B, and 12 dots in A or B. Thus we have $P(A)=8\\P(B)=7\\P(A ∩ B)=3\\P(A ∩ C)=2\\P(B ∩ C)=3$ Then $P(A ∩ B ∩ C)=1\\P(A \cup B \cup C)=15$ Since $8+7+7-3-2-3+1=15$ The formula is: $P(A \cup B \cup C)=P(A)+P(B)+P(C)-P(A ∩ B)-P(B ∩ C)-P(A∩C)+P(A∩B∩C)$