Machine-translated by Google. Questions are authored in English.
Top

Discussion

If \(P(A | B) = P(B)\), then :

  • A.\(P(B | A) = P(A)\)
  • B.A and B are independent events
  • C.\(P^{2}(A) \le P(B)\)
  • D.\(P^{2}(B) \le P(A)\)

Answer: D

The answer is \(P^{2}(B) \le P(A)\).

\(P(A | B) = P(A \cap B)/P(B) = P(B)\) gives \(P(A \cap B) = P^{2}(B)\). Since \(A \cap B \subseteq A\),

\[ P^{2}(B) = P(A \cap B) \le P(A) \]

The others need not hold. Take \(P(A) = 0.7\), \(P(B) = 0.4\) and \(P(A \cap B) = 0.16\), which is consistent and gives \(P(A | B) = 0.4 = P(B)\). Then \(P(B | A) = 0.16/0.7 \approx 0.23 \ne P(A)\); A and B are not independent, since \(P(A)P(B) = 0.28 \ne 0.16\); and \(P^{2}(A) = 0.49 \gt P(B)\).

No comment is present. Be the first to comment.
Loading…

Post your comment

Please log in or register to post a comment.