Question

If $U=\{1,2,3,4,5,6,7,8,9,10\};A=\{1,3,5,7,9\}$ and then find $A\text{'}$also find $n(A\text{'})$.

Answer 1

Here $U=\{1,2,3,4,5,6,7,8,9,10\};A=\{1,3,5,7,9\}$

Elements that are not available in set $A$ but in the universal set, are $2,4,6,8,10$

Complement of a set: The complement of a set is the set of elements present in the universal set but not in the given set. The complement of a set A is written as A’ and is read as a complement of set A.

Thus $A\text{'}=\{2,4,6,8,10\}$

Now $n\left(A\right)=5\Rightarrow n(A\text{'})=10-5=5$

Hence, the value of $n(A\text{'})$ is $5.$