A and B are any two non-empty sets and A is proper subset of B. If n(A) = 5, then the minimum possible value of n(A∆ B) is
Solution
Since
\[ A \subset B \]
therefore,
\[ A \cap B = A \]
and
\[ A \Delta B = (A-B)\cup(B-A) \]
But,
\[ A-B=\Phi \]
Hence,
\[ A \Delta B = B-A \]
Since \(A\) is a proper subset of \(B\), set \(B\) must contain at least one extra element.
Therefore,
\[ n(A \Delta B)=1 \]
Answer
\[ \boxed{1} \]