#include<bits/stdc++.h>
using namespace std;

inline int read()
{
	int x=0,f=1;
	char c=getchar();
	while(c<'0' || c>'9')
	{
		if(c=='-') f=-1;
		c=getchar();
	}
	while(c>='0' && c<='9')
	{
		x=x*10+c-'0';
		c=getchar();
	}
	return x*f;
}

const int N=3e5+5;
int n;
int a[N];

int main()
{
	int T=read();
	while(T--)
	{
		n=read();
		for(int i=1;i<=n;i++) a[i]=read();
		double minn=1e9+1;
		int pos=-1;
		for(int i=1;i<=n;i++)
			if(a[i]<minn)
				minn=a[i], pos=i;
		long long s1=0, s2=0, s3=0;
		for(int i=pos-1;i<=n;i++) s1+=a[i];
		for(int i=1;i<=pos+1;i++) s2+=a[i];
		for(int i=1;i<=n;i++) s3+=a[i];
		double ans=(double)s1/(n-pos+2);
		ans=max(ans,(double)s2/(pos+1));
		ans=max(ans,(double)s3/n);
		printf("%.20f",ans);
	}
	return 0;
}