Statistics

OR Probability Calculator

Find the probability that at least one of two events occurs.

Calculated Output

P(A or B) 0.65

Formula: P(A or B) = P(A) + P(B) − P(A and B)

Step-by-Step Breakdown

1. Values used:

2. P(A) = 0.5

3. P(B) = 0.3

4. P(A and B) = 0.15

6. P(A or B) = 0.65

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The math behind it

P(A or B) = P(A) + P(B) − P(A and B). For mutually exclusive events the overlap is 0.

0.5 + 0.3 − 0.15 = 0.65.

Mutually exclusive events?

Set P(A and B) = 0; then just add the probabilities.