## Question

Let *X *is a set containing n elements. A subset *P* of set *X* is chosen at random. The set *X* is then reconstructed by replacing the elements of set *P*and another set *Q* is chosen at random then find the number of ways to form sets such that

### Solution

it means every element would be either included in *P* or in*Q* or both so for every elements, there are 3 choices.

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