Question

What is the probability that either event will occur?

First, find the probability of event A.
A
B
18
6
12
P(A) = [?]
Enter as a decimal rounded to the nearest hundredth.

Answer 1

• P(A) = 0.50
• P(B) = 0.33
• P(A or B) = 0.83

Explanation:

You want the probability of events A and B, and the probability of either event, given their frequencies are 18 and 12 out of 36 trials.

Probability of A

The probability of event A is the ratio of the number of times A occurs (18) out of the total number of trials (18+12+6). That probability is ...

P(A) = 18/36 = 1/2

P(A) = 0.50

Probability of B

Similarly, the probability of B is the ratio 12/36:

P(B) = 12/36 = 1/3

P(B) ≈ 0.33

Probability of Either

The events have no overlap in the diagram, so the probability of either is the sum of their individual probabilities:

P(A or B) = P(A) +P(B)

P(A or B) = 0.50 +0.33

P(A or B) = 0.83

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