MCQ
If A and B are two disjoint sets, then $\text{n(A}\cup\text{B)}$ is equal to:
- A$\text{n(A) + n(B)}$
- B$\text{n(A) + n(B)} - \text{n(A}\cap\text{B)}$
- C$\text{n(A) + n(B) + n(A}\cap\text{B)}$
- D$\text{n(A) n(B)}.$
Solution:
Two sets are disjoint if they do not have a common element in them, i.e., $\text{A}\cap\text{B}=\phi.$
$\therefore\text{n(A}\cup\text{B) = n(A) + n(B)}.$
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