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Sets — Maths STD 11 Science — Question

CBSE BoardEnglish MediumSTD 11 ScienceMathsSets1 Mark
MCQ
If $A$ and $B$ are two disjoint sets, then $\text{n(A}\cup\text{B)}$ is equal to:
  • ✓
    $\text{n(A) + n(B)}$
  • B
    $\text{n(A) + n(B)} - \text{n(A}\cap\text{B)}$
  • C
    $\text{n(A) + n(B) + n(A}\cap\text{B)}$
  • D
    $\text{n(A) n(B)}.$
✓

Answer

Correct option: A.
$\text{n(A) + n(B)}$
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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