Probability of the union of events

P(A\cup B)=P(A)+P(B)-P(A\cap B)

Result unit: — ($\langle 0,1\rangle$)

What it describes

The probability of the union of events with the intersection subtracted.

P(A), P(B)

probabilities of the events

P(A\cap B)

probability of the intersection

When adding the probabilities of two events, the intersection is counted twice — so we subtract it. For disjoint events

P(A\cap B)=0

The probability of "A or B".

P(A)=0.5

P(B)=0.4

P(A\cap B)=0.2

. Find

P(A\cup B)

Substitution

0.5+0.4-0.2

Result

P(A\cup B)=0.7

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