#include <bits/stdc++.h>
#include <functional>
#include <iomanip>
#include <utility>
#include <vector>
#define x first
#define y second

using namespace std;

typedef double ld;
typedef unsigned long ul;
typedef long long ll;
typedef unsigned long long ull;
typedef pair<ll, ll> pll;

const int maxn = 2e5 + 50;
const ll inf = 0x3f3f3f3f3f3f;
const vector<pll> dxy = {{-1, 0}, {1, 0}, {0, 1}, {0, -1}};

ll a[maxn], pre[maxn];

void solve() {
  ll n;
  cin >> n;
  ll lp, rp, pi, mna = inf;
  for (ll i = 1; i <= n; i++) {
    cin >> a[i];
    pre[i] = pre[i - 1] + a[i];
    if (mna > a[i]) {
      pi = lp = rp = i;
      mna = a[i];
    }
  }
  ll sum = 0, len = 0, llp = lp, rrp = rp;
  ld rcur = 0.0, lcur = 0.0;
  while (lp >= 1) {
    sum += a[lp];
    len++;
    if (1.0 * sum / len > lcur) {
      lcur = 1.0 * sum / len;
      llp = lp;
    }
    lp -= 1;
  }
  sum = 0, len = 0;
  while (rp <= n) {
    sum += a[rp];
    len++;
    if (1.0 * sum / len > rcur) {
      rcur = 1.0 * sum / len;
      rrp = rp;
    }
    rp += 1;
  }
  auto getavl = [&](ll r, ll l) {
    return 1.0 * (pre[r] - pre[l - 1]) / (r - l + 1);
  };

  ld ans = max(getavl(rrp, pi - 2), getavl(pi + 1, llp));
  ans = max(ans, getavl(rrp, llp));
  cout << fixed << setprecision(12) << ans << '\n';
}

void init() {
  // init_primes();
}

/*
TC4:

0 6 7
8 7 8
9 8 9
*/

int main(void) {
  ios::sync_with_stdio(false);
  cin.tie(0);
  init();
  int _t = 1;
  cin >> _t;
  cin.get();
  while (_t--)
    solve();

  return 0;
}