taskJ

#include<bits/stdc++.h>

#define endl "\n"
using namespace std;
using ll = long long;
using ld = long double;
using pii = pair<int, int>;

constexpr int N = 1e5 + 5;

vector<ld> pref;
int n, q, l, r;

ld get(ld cl, ld cr) {
  return (cr - cl + 1) / (pref[cr] - pref[cl - 1]);
}

void Solve() {
  cin >> n;
  pref.resize(n + 1);
  pref[0] = 0;
  for (int i = 1; i <= n; i++) {
    cin >> pref[i];
    pref[i] = 1 / pref[i];
    pref[i] += pref[i - 1];
  }
  cin >> q;
  while(q--) {
    cin >> l >> r;
    l++, r++;
    cout << fixed << setprecision(20) << get(l, r) << endl;
  }
}

int main() {
  ios::sync_with_stdio(false);
  cin.tie(nullptr);
  cout.tie(nullptr);
  // cin >> t;
  // while(t--)
  //auto start = chrono::high_resolution_clock::now();
    Solve();
  //auto end = chrono::high_resolution_clock::now();
  //cout << endl << (chrono::duration_cast<chrono::duration<double>>(end - start)).count();
  return 0;
}