(* Mean inequalities. *)

Lemma lerif_AGM_scaled (I : finType) (A : pred I) (E : I -> R) (n := #|A|) :
{in A, forall i, 0 <= E i *+ n} ->
\prod_(i in A) (E i *+ n) <= (\sum_(i in A) E i) ^+ n
?= iff [forall i in A, forall j in A, E i == E j].