#include<bits/stdc++.h>
using namespace std;
// #define int long long
#define endl '\n'
const int N = 3e5 + 10;
using ll = long long;
using db = double;

const int inf = 1 << 30;

int n, a[N];
ll pre[N];
void solve() {
    cin >> n;
    int mi = a[1], pos = 1;
    for (int i = 1; i <= n; ++i) {
        cin >> a[i];
        pre[i] = pre[i - 1] + a[i];
        if (a[i] < mi) {
            mi = a[i];
            pos = i;
        }
    }
    db ans = 1.0 * pre[n] / n;
    ans = max(ans, 1.0 * (pre[n] - pre[pos - 2]) / (n - pos + 2)); // [pos - 1, n]
    ans = max(ans, 1.0 * pre[pos + 1] / (pos + 1)); // [1, pos + 1]
    cout << fixed << setprecision(20) << ans << endl;
}
signed main() {
    ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);
    int _ = 1;
    cin >> _;
    while(_--) solve();
}