Let $M_{k}^{[r]}({\mathbf{A}},{\mathbf{\Phi}},{\mathbf{\omega}}):=( \sum_{j=1}^{k} \omega_j \ \Phi_j ( A_j^{r} ))^{1/r}$ ($r \in {\mathbf{R}} \backslash \{0 \}$) be a weighted power mean of positive operators $A_j$ with ${\mathsf{Sp}}(A_j) \subseteq [m,M]$ for some scalars $0