Question

If A = {1,2,3,4,5,6}, then the number of subsets of A which contain at least two elements is

• A. 64
• B. 63
• C. 57
• D. 58

Answer 1

Answer: (C)

Total number of subsets of $A$ is $2^{n(A)}=2^6=64$
Number of subsets of A which contain at least two elements is
$64-\left({}^6{C}_0+{}^6{C}_1\right)$
$=64-(1+6)$
$=57$