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If A and B are independent events such that P(A∣B)=13P(A|B) = \frac{1}{3} and P(B)=12P(B) = \frac{1}{2}, then the value of P(A∩B)P(A \cap B) is equal to

Solution

✅ Correct Option: 2

Events AA and BB are independent, with P(A∣B)=13P(A|B) = \frac{1}{3} and P(B)=12P(B) = \frac{1}{2}.

For independent events, P(A∣B)=P(A)P(A|B) = P(A).

(Translation: If AA and BB don't affect each other, then the probability of AA given BB has happened is just the probability of AA)

Since P(A∣B)=13P(A|B) = \frac{1}{3}, this means P(A)=13P(A) = \frac{1}{3}.


For independent events:

P(A∩B)=P(A)×P(B)P(A \cap B) = P(A) \times P(B)

Substituting the values:

P(A∩B)=13×12P(A \cap B) = \frac{1}{3} \times \frac{1}{2}

P(A∩B)=16P(A \cap B) = \frac{1}{6}


Alternatively, using the conditional probability formula:

P(A∣B)=P(A∩B)P(B)P(A|B) = \frac{P(A \cap B)}{P(B)}

Rearranging:

P(A∩B)=P(A∣B)×P(B)P(A \cap B) = P(A|B) \times P(B)

P(A∩B)=13×12P(A \cap B) = \frac{1}{3} \times \frac{1}{2}

P(A∩B)=16P(A \cap B) = \frac{1}{6}


Therefore, P(A∩B)=16P(A \cap B) = \frac{1}{6}.

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