On finite groups whose every normal subgroup is a union of the same number of conjugacy classes (Q1862669)

If \(G\) is a finite group and if \(H\) is a nontrivial normal subgroup of \(G\), the authors call \(H\) to be \(n\)-decomposable if \(H\) is the union of \(n\) distinct conjugacy classes of \(G\). They investigate finite groups \(G\) with \(G'\) 3-decomposable and finite nonsimple groups \(G\) in which every nontrivial normal subgroup is \(n\)-decomposable for a fixed \(n\), \(n\leq 4\).