Final answer:
The probability of either mutually exclusive event A or B occurring, P(AUB), is the sum of their individual probabilities: 0.6.
Step-by-step explanation:
For two mutually exclusive events A and B, with P(A) = 0.2 and P(B) = 0.4, the probability of either A or B occurring, denoted P(AUB), is the sum of the individual probabilities. Since events A and B cannot occur at the same time (they are mutually exclusive), we do not need to subtract the intersection (because P(A AND B) = 0). Therefore, P(AUB) = P(A) + P(B).
P(AUB) = 0.2 + 0.4 = 0.6