Question

Let $S=\{1,2,3,4\}$. The total number of unordered pairs of disjoint subsets of $S$ is equal to

• A. $25$
• B. $35$
• C. $42$
• D. $41$

Answer 1

The correct option is D $41$

Given $S=\{1,2,3,4\}$
S is consists of 4 elements
To find the number of unordered pair of disjoint subsets of S
$=\frac{(3^4-1)}{2}+1=\frac{80}{2}+1=41$