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)

57

Answer 2

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
$64- \left({ }^{6} C _{0}+{ }^{6} C _{1}\right)$
$=64-(1+6)$
$=57$