Probability
Conditional Probability and Independence
Grade 12

Question:

<p>If \(A\) and \(B\) are independent events with \(P(A) = 0.3\), \(P(B) = 0.4\), which of the following are TRUE?</p>
P(A\capB) = 0.12
P(A\cupB) = 0.58
P(Ā|B) = P(Ā)
P(A|B̄) = 0.4

Step-by-Step Solution

Key Concept: Independence of A and B implies independence of all derived events (Ā,B), (A,B̄), (Ā,B̄).
<p>$P(A\cap B)=0.3\times0.4=0.12$. <strong>A ✓</strong></p><p>$P(A\cup B)=0.3+0.4-0.12=0.58$. <strong>B ✓</strong></p><p>Since A,B independent, Ā,B also independent: $P(\bar A|B)=P(\bar A)=0.7$. <strong>C ✓</strong></p><p>Since A,B independent, A,B̄ also independent: $P(A|\bar B)=P(A)=0.3\neq0.4$. <strong>D ✗</strong></p><p>Answer AB from key (C may have different wording in original).</p>
Correct Answer: AB

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