#include <bits/stdc++.h>
using namespace std;

void solve() {
    int n;
    scanf("%d", &n);
    vector<long long> a(n + 2); 
    a[0] = LLONG_MAX;
    a[n + 1] = LLONG_MAX;
    for (int i = 1; i <= n; i++) {
        scanf("%lld", &a[i]);
    }
    
    int tip = -1;
    for (int i = 2; i <= n - 1; i++) {
        if (a[i - 1] > a[i] && a[i] < a[i + 1]) {
            tip = i;
            break;
        }
    }

    if (tip == -1) {
        tip = 1; 
    }
    
    vector<long long> pre(n + 2, 0), last(n + 2, 0);
    for (int i = 1; i <= n; i++) {
        pre[i] = pre[i - 1] + a[i];
    }
    for (int i = n; i >= 1; i--) {
        last[i] = last[i + 1] + a[i];
    }
    
    double maxAvg = (double)pre[n] / n;
    
    for (int l = 1; l <= tip - 2; l++) {
        if (a[l] > a[l + 1]) {
            int len = n - l + 1;
            long long sum = pre[n] - pre[l - 1];
            double avg = (double)sum / len;
            if (avg > maxAvg) {
                maxAvg = avg;
            }
        } else {
            break;
        }
    }
    
    for (int r = n; r >= tip + 2; r--) {
        if (a[r] > a[r - 1]) {
            int len = r;
            long long sum = pre[r];
            double avg = (double)sum / len;
            if (avg > maxAvg) {
                maxAvg = avg;
            }
        } else {
            break;
        }
    }

    if (n >= 3) {
        long long sum = a[tip - 1] + a[tip] + a[tip + 1];
        double avg = sum / 3.0;
        if (avg > maxAvg) {
            maxAvg = avg;
        }
    }

    printf("%.20f\n", maxAvg);
}

int main() {
    int t;
    scanf("%d", &t);
    while (t--) solve();
    return 0;
}