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  1. Since \(38 - 23 = 15\text{,}\) we can conclude that the cardinality of the set is \(|A| = 16\) (you need to add one since 23 is included).

  2. Here \(|B| = 3\text{.}\) The three elements are the number 1, the set \(\{2,3,4\}\text{,}\) and the empty set.

  3. We wrote out the elements of the power set \(\pow(C)\) above, and there are 8 elements (each of which is a set). So \(\card{\pow(C)} = 8\text{.}\) (You might wonder if there is a relationship between \(\card{A}\) and \(\card{\pow(A)}\) for all sets \(A\text{.}\) This is a good question which we will return to in Chapter 1.)

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