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JEE Advanced Mathematics Probability 2022 JEE Advanced 2022 (Paper 2)

JEE Advanced Mathematics Question (2022) — Solution

Question

Suppose that Box-I contains 8  red, 3 blue and 5 green balls, Box-ll contains 24 red, 9 blue and 15 green balls, Box-III contains 1 blue, 12 green and 3 yellow balls, Box-IV contains 10 green, 16 orange and 6 white balls. A ball is chosen randomly from Box-l; call this ball b . If b is red then a ball is chosen randomly from Box-ll, if b is blue then a ball is chosen randomly from Box-III, and if b is green then a ball is chosen randomly from Box-IV. The conditional probability of the event 'one of the chosen balls is white' given that the event 'at least one of the chosen balls is green' has happened, is equal to

Options

  1. A. 15 256
  2. B. 3 16
  3. C. 5 52
  4. D. 1 8

Answer

C. 5 52

Step-by-step solution

P Red from Box   I = 8 16 = 1 2 P Blue from Box   I = 3 16 P Green from Box   I = 10 32 = 5 16 Now, P Green from Box   II = 15 48 P Green from Box   III = 12 16 = 3 4 P White from Box   IV = 6 32 = 3 16 Event A : One of the chosen ball is white B : At least one of the chosen ball is green P A B = P A ∩ B P B = 5 16 × 3 16 1 2 × 15 48 + 3 16 × 3 4 + 5 16 × 1 = 5 52

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