#include <bits/stdc++.h>
#define int long long
//#define double long double
using namespace std;

void solve()
{
	int n;
	cin>>n;
	int a[n+1];
	a[0]=1e18;
	double ans=-1;
	int mid=-1,cnt=0,tot=0;
	for(int i=1;i<=n;i++)
	{
		cin>>a[i];
		tot+=a[i];
		if(i==1 or a[i]<a[i-1]) mid=i;
	}

	long double valA=0,valB=0;
	long double sumA=0,sumB=0;
	int ll=1,rr=n;

	for(int i=mid-1;i>=1;i--)
	{
		sumA+=a[i];
		long double vlu=sumA/(mid-i);
		if(vlu>valA)
		{
			valA=vlu;
			ll=i;
		}
	}

	for(int i=mid+1;i<=n;i++)
	{
		sumB+=a[i];
		long double vlu=sumB/(i-mid);
		if(vlu>valB)
		{
			valB=vlu;
			rr=i;
		}
	}

	tot=0;
	for(int i=ll;i<=rr;i++) tot+=a[i];
	ans=(double)tot/(rr-ll+1);

	printf("%.20lf\n",ans);
}

signed main()
{
	int t;
	cin>>t;
	while(t--) solve();
}