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JEE Mains · Maths · STD 11 - 1. set theory

Let \(A =\{1,2,3,4,5,6,7\}\) and \(B =\{3,6,7,9\}\). Then the number of elements in the set \(\{ C \subseteq A : C \cap B \neq \phi\}\) is

  1. A \(111\)
  2. B \(112\)
  3. C \(113\)
  4. D \(114\)
Verified Solution

Answer & Solution

Correct Answer

(B) \(112\)

Step-by-step Solution

Detailed explanation

\(A =\{1,2,3,4,5,6,7\} \text { and }\) \(B =\{3,6,7,9\}\) Total subset of \(A =2^{7}=128\) \(C \cap B =\phi\) when set \(C\) contains the element \(1,2,4,5\) \(\therefore S=\{C \subseteq A ; C \cap B \neq \phi\}\) \(=\operatorname{Total}-(C \cap B=\phi)\) \(=128-2^{4}=112\)