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JEE Advanced Mathematics Probability 2021 JEE Advanced 2021 (Paper 1)

JEE Advanced Mathematics Question (2021) — Solution

Question

Let E ,   F and G be three events having probabilities  P ( E ) = 1 8 , P ( F ) = 1 6  and  P ( G ) = 1 4 ,  and let  P ( E ∩ F ∩ G ) = 1 10 For any event H , if H c denotes its complement, then which of the following statements is (are) TRUE ?

Options

  1. A. P E ∩ F ∩ G c ≤ 1 40
  2. B. P E c ∩ F ∩ G ≤ 1 15
  3. C. P ( E ∪ F ∪ G ) ≤ 13 24
  4. D. P E c ∩ F c ∩ G c ≤ 5 12

Answer

C. P ( E ∪ F ∪ G ) ≤ 13 24

Step-by-step solution

(i) P E ∩ F ∩ G c = P E ∩ F - P E ∩ F ∩ G ≤ P E - 1 10 = 1 8 - 1 10 = 1 40 (ii) P E c ∩ F ∩ G = P ( F ∩ G ) - P ( E ∩ F ∩ G ) ≤ P ( F ) - 1 10 = 1 6 - 1 10 = 1 15 (iii) P E ∪ F ∪ G ≤ P E + P F + P G = 1 8 + 1 6 + 1 4 = 3 + 4 + 6 24 = 13 24 (iv) P E c ∩ F c ∩ G c max = 1 - P ( E ∩ F ∩ G ) min ∵ P ( E ∩ F ∩ G ) min = 1 4 Thus P E c ∩ F c ∩ G c ≤ 3 4

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