#include<bits/stdc++.h>

using namespace std;
#define lowbit(x) x & -x
#define int long long
#define pii pair<int ,int >
#define  fi first
#define se second
#define ull unsigned long long

#define find1(x) __builtin_popcount(x)

const int N = 1e5 + 10, inf = 0x3f3f3f3f, mod = 1e9 + 7,INF=0x3f3f3f3f3f3f3f3f;

mt19937_64 rnd(random_device{}());
uniform_int_distribution<ull> dist(0, ULLONG_MAX); // use dist(rnd)
#define double long double

void solve() {
	int n;
	cin >> n ;
	vector<int > a(n + 1);
	int sum  = 0 ;
	for(int i = 1; i <= n ; i ++)
	{
		cin >> a[i];
		sum += a[i];
	}
	int pos = 0 ;
	for(int i = 2 ; i <= n - 1 ; i ++)
	{
		if(a[i] < a[i - 1] && a[i] < a[i + 1]) pos = i , i = n + 1;
	}
	for(int i = 1 ; i <= n ; i ++) a[i] += a[i - 1];
	double Ans = 0;
	Ans = 1.0 * sum / n;
	Ans = max(Ans , 1.0L * (a[n] - a[pos - 2]) / (n - pos + 2));
	Ans = max(Ans , 1.0L * (a[pos + 1]) / (pos + 1));
	cout << Ans << '\n';
	
}



/*


*/


#undef int
int main() {
  ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);
  cout<<fixed<<setprecision(15);
  
  
  
  int _ = 1;cin >>_;while(_--)
  {
    solve();
  }
  return 0;
}