#include <bits/stdc++.h>

#define int long long 

void solve () {
    int n;
    std::cin >> n;
    std::vector<int> a(n + 2), sum(n + 2);
    for(int i = 1; i <= n; i++) {
        std::cin >> a[i];
        sum[i] = sum[i - 1] + a[i];
    }

    std::vector<int> pre(n + 2), nex(n + 2);
    auto pre1 = pre, nex1 = nex;

    for(int i = 1; i <= n; i++) {
        if(i == 1) {
            pre[i] = a[i];
            pre1[i] = 1;
        }else {
            if(pre[i - 1] >= a[i] * pre1[i - 1]) {
                pre[i] = pre[i - 1] + a[i];
                pre1[i] = pre1[i - 1] + 1;
            }else {
                pre[i] = a[i];
                pre1[i] = 1;
            }
        }
    }
    for(int i = n; i >= 1; i--) {
        if(i == n) {
            nex[i] = a[i];
            nex1[i] = 1;
        }else {
            if(nex[i + 1] >= a[i] * nex1[i + 1]) {
                nex[i] = nex[i + 1] + a[i];
                nex1[i] = nex1[i + 1] + 1;
            }else {
                nex[i] = a[i];
                nex1[i] = 1;
            }
        }
    }

    double ans = 0;
    // for(int i = 2; i < n; i++) {
    //     if(a[i] < a[i - 1] && a[i] < a[i + 1]) {
    //         // std::cout << a[i] << ' ';
    //         ans = std::max(ans, ((double)a[i] + (double)pre[i - 1] + (double)nex[i + 1]) / (1. + (double)pre1[i - 1] + (double)nex1[i + 1]));
    //     }
    // }
    for(int i = 2; i < n; i++) {
        if(pre1[i] + nex1[i] - 1 >= 3) {
            ans = std::max(ans, ((double)pre[i] + (double)nex[i] - (double)a[i]) / ((double)pre1[i] + (double)nex1[i] - 1.));
        }
    }

    // std::cout << ans << '\n';
    printf("%.20f\n", ans);
}

/*
2
4
8 2 7 10
6
9 6 5 3 4 8
*/


signed main () {
    std::ios::sync_with_stdio(false);
    std::cin.tie(nullptr);

    int t = 1;
    std::cin >> t;
    for(int i = 0; i < t; ++i) {
        solve();
    }

    return 0;
}