  Let $B_1$ be a ball of radius $r_1$ in $S^n(\Hy^n)$, and let $B_0$ be a
smaller ball of radius $r_0$ such that $\bar{B_0}\subset B_1$. For $S^n$ we
consider $r_1< \pi$. Let $u$ be a solution of the problem $-\La u =1$ in $\Om
:= B_1\setminus \bar{B_0}$ vanishing on the boundary. It is shown that the
associated functional $J(\Om)$ is minimal if and only if the balls are
concentric. It is also shown that the first Dirichlet eigenvalue of the
Laplacian on $\Om$ is maximal if and only if the balls are concentric.
