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A and B are two candidates seeking admission in IIT. The probability that A is selected is 0.5 and the probability that both A and B are selected is almost 0.3. Is it possible that the probability of B getting selected is 0.9? |
Answer» Let A denote the event that the candidate A is selected and B the event that B is selected. It is given that P (A) = 0.5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (1) P (A ∩ B) ≤ 0.3 . . . . . . . . . . . . . . . . . . . . . . . . . . (2) Now, P (A) + P (B) - P (A ∩ B) = P (A ∪ B) ≤ 1 Or 0.5 + P (B) - P (A ∩ B) ≤ 1 [Using (1)] Or P (B) ≤ 0.5 + P (A ∩ B) ≤ 0.5 + 0.3 [Using (2)] Or P (B) ≤ 0.8 ∴ P (B) cannot be 0.9 |
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