#include<bits/stdc++.h>
#define int long long
using namespace std;
#define IOS ios::sync_with_stdio(false),cin.tie(0),cout.tie(0)
typedef long double ld;
const int N =2e5+10;

void sol(){
    ld n;
    cin>>n;
    vector<int>a(n);
    int minpos=0,min=0x3f3f3f3f;
    for(int i=0;i<n;i++){
        cin>>a[i];
        if(a[i]<min){
            min=a[i];
            minpos=i;
        }
    }
    //cout<<minpos<<' '<<min<<endl;
    ld avg=0,fg=0,sum=0;
    if(a[0]>a[n-1]){
        for(int i=0;i<=minpos+1;i++){
            sum+=a[i];
        }
        avg=sum/(minpos+2);
        for(int i=minpos+2;i<=n;i++){
            ld tmp=(sum+a[i])/(i+1);
            if(tmp>avg){
                avg=tmp;
            }
        }
    }else{
        for(int i=n-1;i>=minpos-1;i--){
            sum+=a[i];
        }
        avg=sum/(n-minpos+1);
        for(int i=minpos-2;i>=0;i--){
            ld tmp=(sum+a[i])/(n-i-1);
            if(tmp>avg){
                avg=tmp;
            }
        }
    }

    printf("%.20LF\n",avg);
}

signed main(){
    IOS;
    int t;cin>>t;
    while(t--){
        sol();
    }
    return 0;
}