A Is A Set Containing n elements. A Subset P of A is Chosen. The Set A is Reconstructed By Replacing The Elements Of P. A Subset Q of A is Again Chosen. The Number Of Ways Of Choosing P and Q so That P ∩ Q = Ï• is

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A is a set containing n elements. A subset P of A is chosen. The set A is reconstructed by replacing the elements of P. A subset Q of A is again chosen. The number of ways of choosing P and Q so that P  Q = Ï• is


Correct option is


For ai ∈ A, we have the following choice: 


Out of these only (ii), (iii) and (iv) imply .  

Therefore, the number of required subset is 3n.



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