Question

If $A$ and $B$ are not disjoint sets, then $n(A \cup B)$ is equal to

• A. $n(A) + n(B)$
• B. $n(A) + n(B) - n(A \cap B)$
• C. $n(A) + n(B) + n(A \cap B)$
• D. $n(A) \,n(B)$

Answer 1

Answer: (B)

$n(A) + n(B) - n(A \cap B)$

Answer 2

Answer (b) $n(A) + n(B) - n(A \cap B)$