#include<iostream>
#include<cstring>
#include<cstdio>
#include<algorithm>
#include<cmath>
#include<map>
#include<vector>
#include<queue>
#include<set>
#include<bitset>
#include<deque>
#include<stack>
#include<unordered_map>
#include<ctime>
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
const int N=3e5+10;
int n,a[N];
int main()
{
	int T;scanf("%d",&T);
	while(T--)
	{
		scanf("%d",&n);
		for(int i=1;i<=n;i++) scanf("%d",&a[i]);
		int t=1;
		for(int i=2;i<=n;i++)
			if(a[i]<a[t]) t=i;
		ld ans=0.0;ll sum=0;
		for(int i=1;i<=t+1;i++) sum+=a[i];
		if((ld)sum/(ld)(t+1)>ans) ans=(ld)sum/(ld)(t+1);
		sum=0;
		for(int i=t-1;i<=n;i++) sum+=a[i];
		if((ld)sum/(ld)(n-t+2)>ans) ans=(ld)sum/(ld)(n-t+2);
		sum=0;
		for(int i=1;i<=n;i++) sum+=a[i];
		if((ld)sum/(ld)(n)>ans) ans=(ld)sum/(ld)(n);
		printf("%.12Lf\n",ans);
	}
	return 0;
}