If A and B are mutually exclusive, and if P(A)=0.3 and P(B)=0.4, what is P(A U B)?
If A and B are mutually exclusive, it means that they cannot both occur at the same time. Therefore, the probability of their union, P(A U B), is equal to the sum of their individual probabilities.
P(A U B) = P(A) + P(B) = 0.3 + 0.4 = 0.7