#include <bits/stdc++.h>
#pragma GCC optimize(2)
using namespace std;

typedef long long LL;
//#define int LL
#define inl inline
const int N = 3e5 + 10;
const int M = N * 2;
//const int mod=998244353;
const int mod = 1000000007;
const double eps = 1e-8;
//const int mod=1e9+7;
typedef pair<int, int> PII;
//const int INF=0x3f3f3f3f;
const LL INF = 0x3f3f3f3f3f3f3f3f;
int n, m;

void become_faster() {
    ios::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
}

int sa[N];
LL pre[N];
void solve() {
    cin>>n;
    LL sum=0;
    for(int i=1;i<=n;i++) {
        cin>>sa[i];
        pre[i]=pre[i-1]+sa[i];
    }

    int p1=0,p2=0;
    for(int i=2;i<=n;i++) {
        if(sa[i]>sa[i-1]) {
            p1=i;
            break;
        }
    }
    for(int i=n-1;i>=1;i--) {
        if(sa[i]>sa[i+1]) {
            p2=i;
            break;
        }
    }
    double res=0;
    res=pre[n]*1.0/n;
    res=max(res,pre[p1]*1.0/p1);
    res=max(res,(pre[n]-pre[p2-1])*1.0/(n-p2+1));
    cout<<fixed<<setprecision(10)<<res<<endl;
}

signed main() {
    become_faster();
    int T = 1;
    //T=read();
    cin>>T;
    //for(int i=1;i<=100;i++)solve(i);
    while (T--) solve();
    return 0;
}