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Conditional probability from given P(A), P(B), P(A and B) or P(A/B)

This type of question, asked 3 times: 11 May 2024 S2, 11 Apr 2026 S2, 15 Apr 2026 S1. All 3 questions below, oldest first.

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  1. Question 1

    11 May 2024 S2

    119
    If A and B are two events such that P(A)=13P(A)=\frac{1}{3}, P(B)=15P(B)=\frac{1}{5}, P(A∪B)=13P(A\cup B)=\frac{1}{3}, then the value of P(A′/B′)+P(B′/A′)P(A'/B')+P(B'/A') is:

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  2. Question 2

    11 Apr 2026 S2

    100
    If events A and B are such that P(A)=14,P(A∩B)=110P(A) = \dfrac{1}{4}, P(A \cap B) = \dfrac{1}{10} and P(A/B)=2P(B/A)P(A/B) = 2P(B/A) then P(B)=P(B) =...........

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  3. Question 3

    15 Apr 2026 S1

    100
    If A and B are two events such that P(A)=23P(A) = \dfrac{2}{3}, P(B)=12P(B) = \dfrac{1}{2} and P(A∣B)=23P(A \mid B) = \dfrac{2}{3}, then P(A′∪B)+P(A∪B′)=P(A' \cup B) + P(A \cup B') =

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