#include<bits/stdc++.h>
#define IOS ios::sync_with_stdio(false),cin.tie(0),cout.tie(0)
#define rep(i,l,r) for(int i=l;i<=r;i++)
#define endl "\n"
#define eb emplace_back
#define int long long
using namespace std;
using ll=long long;
const int N=3e5+3;
int a[N];
void solve()
{
    int n; cin>>n;
    rep(i,1,n) cin>>a[i];
    int sum = 0;
    double ans = 0;
    int pos = 1;
    rep(i,2,n) if(a[i] < a[pos]) pos = i;
    
    rep(i,1,n) sum += a[i];
    ans = max(ans , sum * 1.0 / n);

    sum = 0;
    rep(i,1,pos + 1) sum += a[i];
    ans = max(ans , sum * 1.0 / (pos + 1));

    sum = 0;
    rep(i,pos - 1,n) sum += a[i];
    ans = max(ans , sum * 1.0 / (n - pos + 2));

    //cout<<pos<<endl;
    cout<<fixed<<setprecision(20)<<ans<<endl;
}
signed main(){IOS;int T=1;cin>>T;while(T--)solve();} 
/*
1
9
7 5 10 9 8 7 5 6 8

3 1 2 3 4 5 6 7 8 9 10

8
 7 5 1 3 9 11
6/3
9/4
13/5
18/6
24/7
31/8
39/9
48/10
58/11
*/