#pragma GCC optimize(3, "Ofast", "inline")
#include <iostream>
#include <bits/stdc++.h>
#define IOS ios::sync_with_stdio(false), cin.tie(0), cout.tie(0)
#define INF 0x3f3f3f3f
#define L_INF 0x7f3f3f3f3f3f3f3f
#define db cout << "debug\n";

using namespace std;
const int Mod = 998244353;
using ll = long long;
ll n, s, a[300011], k, l, r;

void solve()
{
    cin >> n;
    s = 0;
    for (int i = 1; i <= n; i++)
    {
        cin >> a[i];
        s += a[i];
    }
    for (int i = 2; i < n; i++)
        if (a[i] < a[i - 1] && a[i] < a[i + 1])
            k = i;
    l = 1;
    r = n;
    while (l < k - 1 && a[l] * (r - l + 1) < s)
    {
        s -= a[l];
        l++;
    }
    while (r > k + 1 && a[r] * (r - l + 1) < s)
    {
        s -= a[r];
        r--;
    }
    cout << fixed << setprecision(16) << (double)(s) / (r - l + 1) << '\n';
}
int main()
{
    IOS;
// freopen("in.txt", "r", stdin);
// freopen("out.txt", "w", stdout);
#ifndef ONLINE_JUDGE
    clock_t start_time = clock();
#endif
    int t = 1;
    cin >> t;
    while (t--)
    {
        solve();
    }
#ifndef ONLINE_JUDGE
    cout << "Used " << (double)(clock() - start_time) << " ms" << endl;
#endif
    return 0;
}