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

Question

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

Quizplus · Accepted Answer

The formula $n(A \cup C) = n(A) + n(C) - n(A \cap C)$ correctly calculates the number of elements in the union of sets A and C by adding the number of elements in each set and subtracting the number of elements they have in common to avoid double counting. Since Henrika is in both A and C, this formula accurately accounts for the shared element.

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

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