#include <bits/stdc++.h>
using namespace std;
const int maxn = 100005;
int n, m;
double x, y, a[maxn];
struct tree {
  int l, r;
  double L, R;
} t[maxn * 4];
tree merge(tree x, tree y) {
  tree z;
  z.l = x.l;
  z.r = y.r;
  z.L = x.L * y.L / (1 - (1 - y.L) * (1 - x.R));
  z.R = x.R * y.R / (1 - (1 - y.L) * (1 - x.R));
  return z;
}
void build(int l, int r, int num) {
  t[num].l = l, t[num].r = r;
  if (l == r) {
    t[num].L = a[l];
    t[num].R = 1 - a[l];
    return;
  }
  int mid = (l + r) >> 1;
  build(l, mid, num * 2);
  build(mid + 1, r, num * 2 + 1);
  t[num] = merge(t[num * 2], t[num * 2 + 1]);
}
void change(int pos, double val, int num) {
  if (t[num].l == t[num].r) {
    t[num].L = val;
    t[num].R = 1 - val;
    return;
  }
  int mid = (t[num].l + t[num].r) >> 1;
  if (pos <= mid)
    change(pos, val, num * 2);
  else
    change(pos, val, num * 2 + 1);
  t[num] = merge(t[num * 2], t[num * 2 + 1]);
}
tree ask(int L, int R, int num) {
  if (L <= t[num].l && t[num].r <= R) return t[num];
  int mid = (t[num].l + t[num].r) >> 1;
  if (R <= mid)
    return ask(L, R, num * 2);
  else if (mid < L)
    return ask(L, R, num * 2 + 1);
  else
    return merge(ask(L, R, num * 2), ask(L, R, num * 2 + 1));
}
int main() {
  cin >> n >> m;
  for (int i = 1; i <= n; ++i) {
    cin >> x >> y;
    a[i] = x / y;
  }
  build(1, n, 1);
  while (m--) {
    int opt, d;
    cin >> opt;
    if (opt == 1) {
      cin >> d >> x >> y;
      change(d, x / y, 1);
    } else {
      int l, r;
      cin >> l >> r;
      printf("%.8f\n", ask(l, r, 1).L);
    }
  }
  return 0;
}
