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NTA Abhyas JEE Main2020MathematicsSets and RelationsPractice

Let n ( A ) denotes the number of elements in the set A . If n A = 4 ,   n B = 5 and n A ∩ B = 3 , then n [ ( A × B ) ∩ ( B × A ) ] is equal to

Options

  1. A8
  2. B9
  3. C10
  4. D11

Correct answer

B. 9

Step-by-step solution

Given, n A = 4 , n B = 5 and n A ∩ B = 3 ∴ n A × B ∩ B × A = n A ∩ B × B ∩ A = 3 2 = 9

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