Assume that event A occurs with probability 0.4 and event B occurs with probability 0.5. Assume that A and B are disjoint events.

The probability that either event occurs (A or B) is

A. 0.0
B. 0.7
C. 0.9
D. 1.0.

easy to say they do not happen

1-pA = .6
1-pB = .5
so probability that neither happens is
.3
so probability that at least one happens is 1-.3 = .7

Damon, thank you!

To find the probability that either event A or event B occurs, we can use the formula for the probability of the union of two disjoint events:

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

Given that event A occurs with probability 0.4 and event B occurs with probability 0.5, and since A and B are disjoint, we have:

P(A or B) = P(A) + P(B) = 0.4 + 0.5 = 0.9

Therefore, the probability that either event A or event B occurs is 0.9.

So, the correct answer is C. 0.9.

To find the probability that either event A or event B occurs, we can use the addition rule of probability for disjoint events.

The addition rule states that if two events A and B are disjoint (mutually exclusive), meaning they cannot happen at the same time, then the probability of either event A or event B occurring is equal to the sum of their individual probabilities.

In this case, event A and event B are disjoint, so we can simply add their probabilities to find the probability that either event occurs.

Probability(A or B) = Probability(A) + Probability(B)

Given: Probability(A) = 0.4 and Probability(B) = 0.5

Probability(A or B) = 0.4 + 0.5 = 0.9

Therefore, the probability that either event A or event B occurs is 0.9.

Therefore, the correct answer is C. 0.9.