#include<iostream>
#include<cstring>
#include<cmath>
#include<cstdio>
#include<vector>
#include<map>
#include<algorithm>

#pragma GCC optimize("Ofast,no-stack-protector,unroll-loops,fast-math")
#pragma GCC target("sse,sse2,sse3,ssse3,sse4.1,sse4.2,avx,avx2,popcnt,tune=native")
using namespace std;
typedef long long LL;
typedef unsigned long long ULL;
typedef double db;

const int N = 3e5 + 10;
int n , a[N] , pos;

void Asuka()
{
	cin >> n;
	cout.precision(20);
	db ans1 = 0 , ans2 = 0 , ans3 = 0;
	for(int i = 1 ; i <= n ; i ++)
		cin >> a[i];
	for(int i = 2 ; i < n ; i ++){
		if(a[i] < a[i - 1] && a[i] < a[i + 1]){
			pos = i;
			break;
		}
	}
	for(int i = 1 ; i <= pos ; i ++){
		ans1 += a[i];
	}
	ans1 = ans1 / (1.0 * pos);
	for(int i = pos ; i <= n ; i ++){
		ans2 += a[i];
	}
	ans2 = ans2 / (1.0 * (n - pos + 1));
	for(int i = 1 ; i <= n ; i ++){
		ans3 += a[i];
	}
	ans3 = ans3 / (1.0 * n);
	cout << fixed << max({ans1 , ans2 , ans3}) << '\n';
	return;
}

signed main()
{
	ios::sync_with_stdio(false);
	cin.tie(0);
	cout.tie(0);

	int t = 1;
	cin >> t;
	while(t --){
		Asuka();
	}
	return 0;
}