#include <bits/stdc++.h>
#include <iomanip>
#include <iterator>
#include <vector>
using namespace std;
typedef long long ll;
#define int long long
typedef pair<int, int> P;
const int MAX_N = 3e5 + 5;
const int mod = 1e9 + 7;
double a[MAX_N];
void solve()
{
    int n;
    cin >> n;
    vector<double> v;

    for (int i = 0; i < n; ++i)
    {
        cin >> a[i];
    }
    double sum = 0;
    // double cnt = 0;
    double ans = 0;
    for (int i = 0; i < n; i++)
    {
        if (i + 1 < n && i > 0 && a[i] < a[i - 1] && a[i] < a[i + 1])
        {
            // cout << "i: " << i << endl;
            int f = i;
            double ans1 = a[f + 1] + a[f];
            // cout << "ans1: " << ans1 << endl;
            double cnt1 = 2.0;
            while (a[f] < a[f - 1] && a[f - 1] >= 0)
            {
                ans1 += a[f - 1];
                cnt1++;
                f--;
            }
            v.push_back(ans1 / cnt1);
            // cout << ans1 << ' ' << cnt1 << endl;
            double cnt2 = 2.0;
            f = i;
            double ans2 = a[f - 1] + a[f];
            while (f + 1 < n && a[f + 1] > a[f])
            {
                ans2 += a[f + 1];
                cnt2++;
                f++;
            }
            // cout << ans2 << ' ' << cnt2 << endl;
            v.push_back(ans2 / cnt2);
            v.push_back((ans1 + ans2 - a[i] - a[i - 1] - a[i + 1]) / (cnt1 + cnt2 - 3));
        }
    }
    sort(v.rbegin(), v.rend());
    // cout << v[0] << endl;
    cout << fixed << v[0] << setprecision(10) << endl;
}

signed main()
{
    ios::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);

    int t = 1;
    cin >> t;
    while (t--)
    {
        solve();
    }
    return 0;
}