#include<cstdio>
#include<cstring>
#include<algorithm>
#include<cmath>
#define INF 0x3f3f3f3f*1.0
using namespace std;
double getdistence(int x1,int y1,int x2,int y2){
    double xx=sqrt((x1-x2)*(x1-x2)+(y1-y2)*(y1-y2));
    return xx;
}
int n;
double kill;
struct Node{
    int x,y,p;
}node[1111];
bool visit[1111][1111],vis[1111];
double dis[1111][1111],path[1111][1111];
int pre[1111];
void init(){
    memset(visit,0,sizeof(visit));
    memset(vis,0,sizeof(vis));
    memset(path,0,sizeof(path));
    kill=0.0;
    for(int i=1;i<=n;i++)
            scanf("%d %d %d",&node[i].x,&node[i].y,&node[i].p);
    for(int i=1;i<=n;i++)
        for(int j=1;j<=n;j++)
            dis[i][j]=getdistence(node[i].x,node[i].y,node[j].x,node[j].y);
}
void prim(){
    double dist[1111];
    vis[1]=1;
    for(int i=1;i<=n;i++){
        dist[i]=dis[1][i];
        pre[i]=1;
    }
    int p,k;
    p=-1;
    double minn;
    for(int i=1;i<n;i++){
        minn=INF;
        for(int j=1;j<=n;j++){
            if(!vis[j]&&minn>dist[j]){
                    minn=dist[j];
                    k=j;
            }
        }
        visit[k][pre[k]]=visit[pre[k]][k]=1;
        kill+=minn;
        vis[k]=1;
        for(int j=1;j<=n;j++){
            if(!vis[j]&&dist[j]>dis[k][j]){
                dist[j]=dis[k][j];
                pre[j]=k;
            }
            if(vis[j]&&j!=k){
                path[j][k]=path[k][j]=max(path[j][pre[k]],dist[k]);
            }
        }
    }
}
void solve(){
    double ans=0.0;
    for(int i=1;i<=n;i++){
        for(int j=1;j<=n;j++){
            if(j!=i){
                if(visit[i][j])
                    ans=max(ans,(node[i].p+node[j].p)*1.0/(kill-dis[i][j]));
                else
                    ans=max(ans,(node[i].p+node[j].p)*1.0/(kill-path[i][j]));
            }
        }
    }
    printf("%.2f\n",ans);
}
int main(){
    int t;
    scanf("%d",&t);
    while(t--){
        scanf("%d",&n);
        init();
        prim();
        solve();
    }
    return 0;
}

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