#include <stdio.h>
#include <string.h>
#include <math.h>
#include <queue>
#include <map>
#include <vector>
#include <algorithm>
#include <bits/stdc++.h>
#include <iostream>
using namespace std;
#define inf 0x3f3f3f3f
typedef long long ll;
const int maxn=1010;struct Edge
{int a,b;double d;bool operator < (const Edge& rhs) const{return d < rhs.d;}
};int x[maxn];
int y[maxn];
int p[maxn];
int n;
Edge e[maxn*maxn];//G是与该节点相连的节点的编号，C是相应的cost
vector<int> G[maxn];
vector<double> C[maxn];int par[maxn];void init(){for(int i=0;i<n;i++){par[i]=i;G[i].clear();C[i].clear();}
}//int find(int x){return x==find(x)?x:par[x]=find(par[x]);}int find(int x)
{if(x!=par[x])par[x] = find(par[x]);return par[x];
}bool unite(int x,int y){x=find(x);y=find(y);if(x==y){return false;}else{par[x]=y;return true;}
}double mst(){int cnt=0;for(int i=0;i<n;i++){for(int j=i+1;j<n;j++){e[cnt].a=i;e[cnt].b=j;e[cnt].d=sqrt((x[i]-x[j])*(x[i]-x[j])+(y[i]-y[j])*(y[i]-y[j]));cnt++;}}
//    cout<<"ss"<<endl;sort(e,e+cnt);init();for(int i=0; i<n; i++){par[i] = i;G[i].clear();C[i].clear();}double ans=0;int cnt2=0;
//    cout<<"aa"<<endl;for(int i=0;i<cnt;i++){if(unite(e[i].a,e[i].b)){G[e[i].a].push_back(e[i].b);C[e[i].a].push_back(e[i].d);G[e[i].b].push_back(e[i].a);C[e[i].b].push_back(e[i].d);ans+=e[i].d;cnt2++;if(cnt2==n-1) break;}}//    cout<<ans<<endl;return ans;
}double costs[maxn][maxn];
vector<int> nodes;//u是现在在搜索的节点，fa是u的父节点(从哪来)，facost是之前来的那条路的cost
void dfs(int u, int fa, double facost)
{for(int i = 0; i < nodes.size(); i++){int x = nodes[i];costs[u][x] = costs[x][u] = max(costs[x][fa], facost);}nodes.push_back(u);for(int i = 0; i < G[u].size(); i++){int v = G[u][i];if(v != fa)dfs(v, u, C[u][i]);}
}int main(){int t;scanf("%d",&t);while(t--){scanf("%d",&n);for(int i=0;i<n;i++){scanf("%d%d%d",&x[i],&y[i],&p[i]);}
//        cout<<"hh"<<endl;double total=mst();memset(costs,0,sizeof(costs));nodes.clear();dfs(0, -1, 0);double ans = -1;for(int i=0; i<n; i++){for(int j=i+1; j<n; j++){ans = max(ans,(p[i]+p[j])/(total-costs[i][j]));}}printf("%.2lf\n",ans);}return 0;
}