#include<bits/stdc++.h>
#define rep(i,a,b) for(int i=(a);i<=(b);i++)
#define per(i,a,b) for(int i=(a);i>=(b);i--)
#define ll long long
using namespace std;
const int N=300005;
int n,a[N];
void solve(){
    scanf("%d",&n);
    rep(i,1,n) scanf("%d",&a[i]);
    ll s1=0,s2=0;
    int p=min_element(a+1,a+n+1)-a;
    rep(i,1,p) s1+=a[i];
    rep(i,p,n) s2+=a[i];
    double as=max(1.0*s1/p,1.0*s2/(n-p+1));
    as=max(as,1.0*(s1+s2-a[p])/n);
    printf("%lf\n",as);
}
int main(){
    int T;
    scanf("%d",&T);
    while(T--) solve();
}