#include <bits/stdc++.h>

using namespace std;
#define int long long
#define rep(i, a, b) for(int i=(a);i<=(b);++i)
#define sz(x) (int)x.size()
#define endl "\n"
const int N = 2e5, mod = 1e9 + 7, inf = 1e18;

void solve() {
    int n;
    cin>>n;
    vector<int> a(n+5);
    rep(i,1,n) cin>>a[i];
    vector<int> pre(n+5);
    rep(i,1,n) pre[i]=pre[i-1]+a[i];

    vector<int> f(n+1),g(n+1);

#define db double
    auto chk=[&](db x){
        for(int i=1;i<=n;){
            if(a[i+1]==a[i]){
                i++;
                continue;
            }
            int lo=i+1;
            while(lo<=n && a[lo]<a[lo-1]) lo++;
            int ro=lo;int lb=lo-1;
            db mx=-inf;
            while(ro<=n && a[ro]>a[ro-1]){
                mx=max(1.0*pre[ro]-x*ro,mx);
                ro++;
            }
            if(ro-i<3){
                i=ro;
                continue;
            }
            for(int j=i;j<lb;j++){
                db ans2=pre[j-1]-(j-1)*x;
                if(ans2<=mx) return true;
            }

            i=ro;
        }
        return false;
    };

    db lo=0,ro=1e9;
    while((ro-lo)>1e-9){
        db mid=(lo+ro)/2;
        if(chk(mid)) lo=mid;
        else ro=mid;
    }
    cout<<setprecision(10)<<lo<<endl;
}

signed main() {
    ios::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    int64_t tt = 1;
    cin >> tt;
    rep(kase, 1, tt) solve();
}
/*
 2
 4
 8 2 7 10
 6
 9 6 5 3 4 8
 */