#include <algorithm>
#include <iomanip>
#include <iostream>
#include <vector>
using LL = long long;
template<typename T>
void upd_max(T &a, T b) { if (a < b) a = b; }
constexpr int N = 3E5;
int a[N + 1];
LL l_s[N + 1];
int l_l[N + 1];
LL r_s[N + 1];
int r_l[N + 1];
void solve()
{
	int n; std::cin >> n;
	for (int i = 1; i <= n; ++i)
		std::cin >> a[i];
	for (int i = 1; i <= n; ++i)
		if (i > 1 && a[i - 1] > a[i])
			l_l[i] = l_l[i - 1] + 1,
			l_s[i] = l_s[i - 1] + a[i];
		else
			l_l[i] = 1,
			l_s[i] = a[i];
	for (int i = n; i; --i)
		if (i < n && a[i] < a[i + 1])
			r_l[i] = r_l[i + 1] + 1,
			r_s[i] = r_s[i + 1] + a[i];
		else
			r_l[i] = 1,
			r_s[i] = a[i];
	long double ans = 0;
	for (int i = 1; i <= n; ++i)
		if (l_l[i] > 1 && r_l[i] > 1)
			upd_max(ans, static_cast<long double>(l_s[i] + r_s[i] - a[i]) / (l_l[i] + r_l[i] - 1));
	std::cout << ans << "\n";
}
int main()
{
	std::ios::sync_with_stdio(false), std::cin.tie(nullptr);
	int t; std::cin >> t;
	std::cout << std::fixed << std::setprecision(10);
	while (t--) solve();
}