Y(X =2h d(X j )=mean travel time to(from)closest facility Find X∈ G such that for all X∈G, V(X)≤J(X) k is a k-median ofG(N, a )with a given h=(h,h , .,h,)J(Xk ) ≡ hjd(Xk j =1 n ∑ , j) = mean travel time to (from) closest facility Find Xk* ∈G such that for all Xk ∈G, J(Xk* ) ≤ J(Xk ) Xk * is a k - median of G(N, A) with a given h = (h1,h2,...,hn)