#include <bits/stdc++.h>
using namespace std;
const long long mod = 10007;
const long long inf = 1e16;
const long long ninf = LLONG_MIN;
const long double eps = 1e-10;
const long long N = 1000005;
const long long LOGN = 19;
const long double PI = 3.14159265358979323846;
long long mul(long long a, long long b) { return (a * b) % mod; }
long long add(long long a, long long b) {
  a += b;
  if (a >= mod) a -= mod;
  if (a < 0) a += mod;
  return a;
}
long long n, q;
long double p[N];
pair<long double, long double> st[N];
bool is(long double x) { return (abs(x) <= eps); }
pair<long double, long double> merge(pair<long double, long double> l,
                                     pair<long double, long double> r) {
  long double l1 = l.first, r1 = l.second, l2 = r.first, r2 = r.second;
  if (is(l1 + 1) && is(r1 + 1)) return r;
  if (is(l2 + 1) && is(r2 + 1)) return l;
  long double rec = (l2 - 1) * r1 + 1;
  if (is(rec)) return {0, 0};
  long double x = (l1 * l2) / (rec);
  long double y = r2 + (r1 * (1 - r2) * (l2)) / rec;
  return {x, y};
}
void update(long long id, long long s, long long e, long long x,
            long double v) {
  if (s == e) {
    st[id] = {v, v};
    p[s] = v;
    return;
  }
  long long m = (s + e) >> 1;
  if (x <= m) {
    update(id + id, s, m, x, v);
  } else {
    update(id + id + 1, m + 1, e, x, v);
  }
  st[id] = merge(st[id + id], st[id + id + 1]);
}
pair<long double, long double> query(long long id, long long s, long long e,
                                     long long l, long long r) {
  if (s > e || s > r || e < l) {
    return {-1, -1};
  }
  if (l <= s && e <= r) {
    return st[id];
  }
  long long m = (s + e) >> 1;
  return merge(query(id + id, s, m, l, r), query(id + id + 1, m + 1, e, l, r));
}
int main() {
  ios_base::sync_with_stdio(0);
  cin >> n >> q;
  cout << fixed << setprecision(11);
  for (int i = 0; i < n; i++) {
    long double v, a, b;
    cin >> a >> b;
    v = a / b;
    update(1, 0, n - 1, i, v);
  }
  for (int i = 0; i < q; i++) {
    long long t;
    cin >> t;
    if (t == 1) {
      long double v, a, b, in;
      cin >> in >> a >> b;
      in--;
      v = a / b;
      update(1, 0, n - 1, in, v);
    } else {
      long long l, r;
      cin >> l >> r;
      l--;
      r--;
      cout << query(1, 0, n - 1, l, r).first << "\n";
    }
  }
  return 0;
}
