If $A = \{ \text { Klaas, Johan, Henrika, Sarie } \}$ and $C = \{ \text { Hans, Henrika } \}$ , then $n ( A \cup C ) = n ( A ) + n ( C ) - n ( A \cap C )$ .

Question

Quizplus · Accepted Answer

This is the principle of inclusion-exclusion for the cardinality of the union of two sets. $n(A \cup C)$ equals the sum of the cardinalities of the individual sets minus the cardinality of their intersection to avoid double counting the elements that are in both sets.

If A={ Klaas, Johan, Henrika, Sarie }A = \{ \text { Klaas, Johan, Henrika, Sarie } \}A={ Klaas, Johan, Henrika, Sarie }

If $A = \{ \text { Klaas, Johan, Henrika, Sarie } \}$