#include <bits/stdc++.h>

#define rep(i,s,n) for(int i = int(s); i < int(n); i++)
#define rrep(i,s,n) for(int i = int(n) - 1; i >= int(s); i--)
#define all(v) (v).begin(), (v).end()

using ll = long long;
using ull = unsigned long long;
using ld = long double;

template<class T>
bool chmin(T &a, T b) {
    if(a <= b) return false;
    a = b;
    return true;
}

template<class T>
bool chmax(T &a, T b) {
    if(a >= b) return false;
    a = b;
    return true;
}

using namespace std;


const ld dinf = 1e10;
const ll linf = 1e18;

void solve(){
    int n; cin >> n;
    vector<ll> a(n);
    rep(i,0,n) cin >> a[i];
    int ctr = -1;
    rep(i,1,n-1){
        if (a[i-1] > a[i] && a[i] < a[i+1]){
            ctr = i;
        }
    }
    assert(ctr != -1);
    vector<ll> rui(n+1,0);
    rep(i,0,n){
        rui[i+1] = rui[i] + a[i];
    }
    auto get = [&](int l, int r){
        if (r - l < 3) return -linf;
        return rui[r] - rui[l];
    };
    ld ans = 0.0;
    rep(l,0,ctr){
        ll sum = get(l,n);
        chmax(ans,sum/ld(n-l));
    }
    rep(r,ctr+2,n+1){
        ll sum = get(0,r);
        chmax(ans,sum/ld(r-0));
    }
    cout << ans << '\n';
}

int main() {
    std::cin.tie(nullptr);
    std::ios::sync_with_stdio(false);
    cout << fixed << setprecision(15);
    int t; cin >> t;
    while (t--){
        solve();
    }
}