#include <bits/stdc++.h>
using namespace std;
int gi() {
  char cc = getchar();
  int cn = 0, flus = 1;
  while (cc < '0' || cc > '9') {
    if (cc == '-') flus = -flus;
    cc = getchar();
  }
  while (cc >= '0' && cc <= '9') cn = cn * 10 + cc - '0', cc = getchar();
  return cn * flus;
}
const int N = 2e5 + 5;
const double eps = 1e-9;
int n, q;
double p[N];
struct Tr {
  double f, g;
} tr[N << 1];
Tr pushup(Tr x, Tr y) {
  Tr u;
  u.f = x.f * y.f / (x.g + y.f - x.g * y.f + eps);
  u.g = x.g * y.g / (x.g + y.f - x.g * y.f + eps);
  return u;
}
Tr query(int x, int l, int r, int ql, int qr) {
  if (ql <= l && r <= qr) return tr[x];
  int mid = (l + r) >> 1;
  if (mid >= qr) return query((x << 1), l, mid, ql, qr);
  if (mid < ql) return query((x << 1 | 1), mid + 1, r, ql, qr);
  return pushup(query((x << 1), l, mid, ql, mid),
                query((x << 1 | 1), mid + 1, r, mid + 1, qr));
}
void update(int x, int l, int r, int wh) {
  if (l == r) {
    tr[x].f = p[l], tr[x].g = 1 - p[l];
    return;
  }
  int mid = (l + r) >> 1;
  if (wh <= mid)
    update((x << 1), l, mid, wh);
  else
    update((x << 1 | 1), mid + 1, r, wh);
  tr[x] = pushup(tr[(x << 1)], tr[(x << 1 | 1)]);
}
void build(int x, int l, int r) {
  if (l == r) {
    tr[x].f = p[l], tr[x].g = 1 - p[l];
    return;
  }
  int mid = (l + r) >> 1;
  build((x << 1), l, mid), build((x << 1 | 1), mid + 1, r);
  tr[x] = pushup(tr[(x << 1)], tr[(x << 1 | 1)]);
}
signed main() {
  n = gi(), q = gi();
  int x, y;
  for (register int i = (1); i <= (n); ++i)
    x = gi(), y = gi(), p[i] = (1.0 * x) / (1.0 * y);
  build(1, 1, n);
  for (register int i = (1); i <= (q); ++i) {
    int opt = gi(), l = gi(), r = gi();
    if (opt == 1) x = gi(), p[l] = (1.0 * r) / (1.0 * x), update(1, 1, n, l);
    if (opt == 2) printf("%.7lf\n", query(1, 1, n, l, r).f);
  }
  return 0;
}
