#include <bits/stdc++.h>

void solve() 
{
    int n;
    std::cin >> n;
    std::vector<int> a(n);
    std::vector<int64_t> pre(n + 1);
    int pos = -1;
    for (int i = 0; i < n; ++i) {
        std::cin >> a[i];
        pre[i + 1] = pre[i] + a[i];
    }
    double ans = (double)pre[n] / n;
    int64_t suml = 0, sumr = 0;
    for (int i = 1; i < n - 1; ++i) {
        if (a[i] < a[i - 1] && a[i] < a[i + 1]) {
            for (int j = 0; j <= i + 1; ++j) {
                suml += a[j];
            }
            for (int j = n - 1; j >= i - 1; --j) {
                sumr += a[j];
            }
            ans = std::max<double>(ans, (double)suml / (i + 2));
            ans = std::max<double>(ans, (double)sumr / (n - i + 1));
            break;
        }
    }
    std::cout.setf(std::ios::fixed);
    std::cout << std::setprecision(15) << ans << '\n';
}

int main() 
{
    std::cin.tie(nullptr)->std::ios::sync_with_stdio(false);
    
    int t;
    std::cin >> t;
    while(t--) {
        solve();
    }
    
    return 0;
}