Question

Let $U=\{x\in N\mid x<20\}$ be the universal set. Let $A=\{x\in N\mid x\text{is prime less than}20\}$,
$B=\{x\in N\mid x\text{is}3n,n\in N,n\le 6\}$,
$C=\{x\in N\mid x=2n–1,n\in N,n\le 10\}$. Then $n\left[\right(A\cup B{)}^{\prime }\cup (A\cap C)]=$

• A. $10$
• B. $11$
• C. $12$
• D. $13$

Answer 1

The correct option is D $13$

$U=\{1,2,3,...,19\}A=\{2,3,5,7,11,13,17,19\}B=\{3,6,9,12,15,18\}C=\{1,3,5,7,...,19\}(A\cup B{)}^{\prime }=U–(A\cup B)=\{1,4,8,10,14,16\}\therefore (A\cup B{)}^{\prime }\cup (A\cap C)=\{1,3,4,5,7,8,10,11,13,14,16,17,19\}$