//#pragma GCC optimize(1)
//#pragma GCC optimize(2)
//#pragma GCC optimize(3,"Ofast","inline")

#include<bits/stdc++.h>

using namespace std;

#define x first
#define y second
#define int long long
#define ll __int128
#define double long double
#define lowbit(x) (x&(-x))
#define log(x) (31^__builtin_clz(x))
#define endl '\n'

typedef pair<int,int>PII;
typedef pair<double,double>PDD;
typedef tuple<double,double,double>TDDD;
typedef tuple<int,int,int>TIII;

const int N = 2e5+10;
const int mod = 1e9+7 , P = 131;
const double PI = acos(-1);
const double eps = 1e-8;

mt19937_64 rng((unsigned int) chrono::steady_clock::now().time_since_epoch().count());//随机数


int read(){
    char c=0;
    int res=0;
    int f=1;
    while(!(c>='0'&&c<='9')){
        if(c=='-'){
            f=-f;
        }
        c=getchar();
    }
    while(c>='0'&&c<='9'){
        res=(res<<3)+(res<<1)+c-'0';
        c=getchar();
    }
    return res*f;
}

void write(int x){
    if(x<0){putchar('-');x=-x;}
    if(x>9) write(x/10);
    putchar(char(x%10+'0'));
}

int n,w[N];
int pre[N];

void solve(){
    cin>>n;

    int minv=1e18,id=0;

    for(int i=1;i<=n;i++){
        cin>>w[i];
        pre[i]=pre[i-1]+w[i];
        if(w[i]<minv){
            minv=w[i];
            id=i;
        }
    }

    double ans=0;

    int l=id,r=id;
    while(l>=1||r<=n){
        l--,r++;
        if(l<1&&r<=n)l=1;
        if(r>n&&l>=1)r=n;
        ans=max(ans,(double)(pre[r]-pre[l-1])/(r-l+1));
    }

    printf("%.12Lf\n",ans);

}

signed main(){
    ios::sync_with_stdio(false);
    cin.tie(0),cout.tie(0);
    int T;
    cin>>T;
    while(T--)solve();

#ifdef GREENQWQ
    cerr<<fixed<<setprecision(10)<<1.0*clock()/CLOCKS_PER_SEC<<endl;
#endif
    return 0;
}