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COMEDK · Maths · 36. Probability

Let \(\mathrm{A}\) and \({B}\) be two events such that \(P(A / B)=\dfrac{1}{2}\) and \(P(B / A)=\dfrac{1}{3}\) and \(P(A \cap B)=\dfrac{1}{6}\) then, which one of the following is not true?

  1. A \(P\left(A^{\prime} \cap B\right)=\dfrac{1}{6}\)
  2. B \(A \text { and } B \text { are independent }\)
  3. C \(\mathrm{A} \text { and } \mathrm{B} \text { are not independent }\)
  4. D \(P(A \cup B)=\dfrac{2}{3}\)
Verified Solution

Answer & Solution

Correct Answer

(C) \(\mathrm{A} \text { and } \mathrm{B} \text { are not independent }\)

Step-by-step Solution

Detailed explanation

Given \(P(A|B) = \dfrac{P(A \cap B)}{P(B)} = \dfrac{1}{2}\) and \(P(A \cap B) = \dfrac{1}{6}\), we have \(\dfrac{1/6}{P(B)} = \dfrac{1}{2}\), which implies \(P(B) = \dfrac{1}{3}\). Given \(P(B|A) = \dfrac{P(A \cap B)}{P(A)} = \dfrac{1}{3}\) and \(P(A \cap B) = \dfrac{1}{6}\), we…