#include<bits/stdc++.h>
using namespace std;
#define fast ios::sync_with_stdio(false),cin.tie(0),cout.tie(0)
#define For(i,j,k) for (int i=(j);i<=(k);i++)
#define rof(i,j,k) for (int i=(j);i>=(k);i--)
#define ull unsigned long long
#define lowbit(x) ((x)&(-(x)))
#define PII pair<int,int>
#define int long long
#define endl "\n"
#define ls rt<<1
#define rs rt<<1|1
typedef long long ll;
const int mod = 998244353;
const double eps = 1e-9;
const int N=2e6+7;
int n,m;
int a[N];
void solve(){
	cin>>n;
    double ans=0;
    int cnt=0;
    int cn=0;
    double mi=0x3f3f3f3f;
    double sum=0;
    for(int i=1;i<=n;i++){
        cin>>a[i];
        if(a[i]<mi) mi=a[i],cnt=i;
    }
    sum=a[cnt];
    ans=a[cnt];
    double tem=sum;
    double an=ans;
    for(int i=cnt+1;i<=n;i++){
        tem+=a[i];
        an=tem/(i-cnt+1);
        if(an>ans){
            ans=an;
            sum=tem;
            cn=i;
        }
    }
    for(int i=cnt-1;i>=1;i--){
        tem+=a[i];
        an=tem/(cn-i+1);
        if(an>ans){
            ans=an;
            sum=tem;
        }
    }
    cout<<fixed<<setprecision(15)<<endl;
    cout<<ans<<endl;
}
signed main(){
	int t=1;
	cin>>t;
	while(t--){
		solve();
	}
}