#include <bits/stdc++.h>
using namespace std;
#define LL long long
#define ULL unsigned long long
#define Enter putchar('\n')
#define spc putchar(' ')
#define pb push_back
#define fi first
#define se second
inline void read(int &num){num=0;int f=1;char ch=getchar();while(ch>'9'||ch<'0'){if(ch=='-')f=-1;ch=getchar();}while(ch>='0'&&ch<='9'){num=(num<<1)+(num<<3)+(ch^48);ch=getchar();}num*=f;}
inline void lread(long long &num){num=0;int f=1;char ch=getchar();while(ch>'9'||ch<'0'){if(ch=='-')f=-1;ch=getchar();}while(ch>='0'&&ch<='9'){num=(num<<1)+(num<<3)+(ch^48);ch=getchar();}num*=f;}
void print(long long num){if(num<0){putchar('-');num=-num;}if(num>9){print(num/10);}putchar((num%10)^48);}
int a[300009];
int main(){
    int T,n;
    read(T);
    while(T--){
        read(n);
        int mi=1e9+1,pos;
        for(int i=1;i<=n;i++){
            read(a[i]);
            if(a[i]<mi){
                mi=a[i];
                pos=i;
            }
        }
        long double ans=0.0,sum=0.0;
        for(int i=pos-1;i<=n;i++){
            sum+=a[i];
        }
        sum/=(n-pos+2);
        ans=max(ans,sum);
        sum=0.0;
        for(int i=1;i<=pos+1;i++){
            sum+=a[i];
        }
        sum/=(pos+1);
        ans=max(ans,sum);
        sum=0.0;
        for(int i=1;i<=n;i++)sum+=a[i];
        printf("%.10Lf\n",max(ans,sum/n));
    }
    return 0;
}