When A and B are considered mutually exclusive, how is P(A or B) calculated?

When A and B are considered mutually exclusive, how is P(A or B) calculated?

• A. P(A) + P(B) - P(A and B)
• B. P(A) + P(B)
• C. P(A) / P(B)
• D. P(A and B)

Answer: (B)

When events A and B are considered mutually exclusive, it means that they cannot occur at the same time. Therefore, the probability of either A or B occurring, denoted as P(A or B), can be calculated simply by adding the probabilities of each event. In this case, P(A or B) equals P(A) plus P(B) because since A and B cannot happen simultaneously, we don't need to subtract the probability of them occurring together (P(A and B)) since it would be zero. This is a fundamental rule in probability for mutually exclusive events, making it straightforward to find the combined probability. Thus, the correct way to express P(A or B) in the context of mutually exclusive events aligns with the understanding that their probabilities aggregate without any overlap.

When events A and B are considered mutually exclusive, it means that they cannot occur at the same time. Therefore, the probability of either A or B occurring, denoted as P(A or B), can be calculated simply by adding the probabilities of each event.

In this case, P(A or B) equals P(A) plus P(B) because since A and B cannot happen simultaneously, we don't need to subtract the probability of them occurring together (P(A and B)) since it would be zero. This is a fundamental rule in probability for mutually exclusive events, making it straightforward to find the combined probability.

Thus, the correct way to express P(A or B) in the context of mutually exclusive events aligns with the understanding that their probabilities aggregate without any overlap.