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1.Set Theory
easy
Given $n(U) = 20$, $n(A) = 12$, $n(B) = 9$, $n(A \cap B) = 4$, where $U$ is the universal set, $A$ and $B$ are subsets of $U$, then $n({(A \cup B)^C}) = $
A
$17$
B
$9$
C
$11$
D
$3$
Solution
(d) $n(A \cup B) = n(A) + n(B) – n(A \cap B) = 12 + 9 – 4 = 17$
Now, $n({(A \cup B)^C}) = n(U) – n(A \cup B) = 20 – 17 = 3$.
Standard 11
Mathematics