// Problem: E. Sakurako, Kosuke, and the Permutation
// Contest: Codeforces - Codeforces Round 981 (Div. 3)
// URL: https://codeforces.com/contest/2033/problem/E
// Memory Limit: 256 MB
// Time Limit: 2000 ms
// 
// Powered by CP Editor (https://cpeditor.org)

#include<iostream>
#include<vector>
#include<map>
#include<queue>
#include<string>
#include<cstring>
#include<algorithm>
#include <iomanip>
#include<numeric>
#define int long long
using namespace std;
const int N = 3e5 + 7;
int a[N];
int s[N];
void solve() {
	int n;
	cin >> n;
	int sum = 0;
	int cnt = n;
	for (int i = 1; i <= n; i++) {
		cin >> a[i];
	}
	for (int i = 1; i <= n; i++) {
		s[i] = s[i - 1] + a[i];
	}

	int idx;

	for (int i = 1; i <= n; i++) {
		if (a[i] < a[i - 1] && a[i] < a[i + 1]) {
			idx = i;
			break;
		}
	}
	
	double res = 1.0 * s[n] / cnt;
	res = max(res, 1.0 * s[idx + 1] / (idx + 1));

	res = max(res, 1.0 * (s[n] - s[idx - 2]) / (n - idx + 2));


	cout << fixed << setprecision(15)<< res << endl;

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