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CBSE Class 12 Math 2023 All Sets Solved Paper

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Question : 8 of 20
Marks: +1, -0
If A and B are two events such that P(A∣B)=2×P(B∣A)P(A\mid B) = 2 \times P(B\mid A) and P(A)+P(B)=23,P(A) + P(B) = \frac{2}{3}, then P(B) is equal to:
Solution:  
P(A∣B)=2×P(B∣A)P(A\mid B)=2 \times P(B\mid A)
⇒P(A∩B)P(B)=2×P(A∩B)P(A)\Rightarrow \frac{P(A\cap B)}{P(B)} = 2 \times \frac{P(A\cap B)}{P(A)}
⇒P(A)=2×P(B)\Rightarrow P(A) = 2 \times P(B)
P(A)+P(B)=23P(A) + P(B) = \frac{2}{3}
⇒3P(B)=23\Rightarrow 3P(B) = \frac{2}{3}
⇒P(B)=29\Rightarrow P(B) = \frac{2}{9}
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