Sets

\[A=\{2,4,6,8\},\qquad B=\{4,k,10\},\] where \(k\) is an integer satisfying \(1\leq k\leq10\).
Given that \[n(B)=3,\qquad n(A\cap B)=2,\]

1. find every possible value of \(k\);

2. state \(A\cap B\) for each permitted value;

3. explain why \(k=4\) and \(k=10\) are not permitted.