1. **Problem:** Given the sample space $\Omega = \{A, B, H\}$ with mutually exclusive events $A, B, H$ and $P(A \cup B) = 0.6$, find $P(H)$. 2. **Formula and rules:** Since $A, B, H$ are mutually exclusive and cover the entire sample space, we have: $$P(A) + P(B) + P(H) = 1$$ Given $P(A \cup B) = P(A) + P(B) = 0.6$, then: $$P(H) = 1 - P(A \cup B) = 1 - 0.6 = 0.4$$ 3. **Answer:** $P(H) = 0.4$ (Option ج).