#include <bits/stdc++.h>
using namespace std;
struct Prob {
  double l, r;
  bool notset;
  void Merge(Prob a, Prob b) {
    l = a.l * b.l / ((1 - (1 - b.l) * a.r));
    r = b.r + ((1 - b.r) * a.r * b.l) / (1 - (1 - b.l) * a.r);
  }
  void Append(Prob a) {
    if (notset) {
      notset = false;
      *this = a;
      return;
    }
    Prob tmp;
    tmp.Merge(*this, a);
    *this = tmp;
  }
  void init() { notset = true; }
} answ;
struct ST {
  int l, r;
  ST *lc, *rc;
  Prob t;
} t[200009];
int n, q;
double p[100009];
ST* initTree(int l, int r) {
  static int cntT = 0;
  ST* it = &t[cntT++];
  it->l = l, it->r = r;
  if (l == r) {
    it->lc = it->rc = nullptr;
    it->t.l = p[l];
    it->t.r = p[l];
  } else {
    int mid = (l + r) >> 1;
    it->lc = initTree(l, mid);
    it->rc = initTree(mid + 1, r);
    it->t.Merge(it->lc->t, it->rc->t);
  }
  return it;
}
void Update(ST* root, int pos) {
  if (pos < root->l || root->r < pos) return;
  if (root->l == root->r) {
    root->t.l = p[pos];
    root->t.r = p[pos];
  } else {
    Update(root->lc, pos);
    Update(root->rc, pos);
    root->t.Merge(root->lc->t, root->rc->t);
  }
}
void Query(ST* root, int l, int r) {
  if (l <= root->l && root->r <= r) {
    answ.Append(root->t);
  } else {
    if (l <= root->lc->r) Query(root->lc, l, r);
    if (root->rc->l <= r) Query(root->rc, l, r);
  }
}
int main() {
  scanf("%d %d", &n, &q);
  for (int i = 1; i <= n; i++) {
    int a, b;
    scanf("%d %d", &a, &b);
    p[i] = a / (double)b;
  }
  ST* root = initTree(1, n);
  int type, l, r, val;
  for (int i = 0; i < q; i++) {
    scanf("%d", &type);
    if (type == 1) {
      scanf("%d %d %d", &val, &l, &r);
      p[val] = l / (double)r;
      Update(root, val);
    } else {
      scanf("%d %d", &l, &r);
      answ.init();
      Query(root, l, r);
      printf("%.11f\n", answ.l);
    }
  }
  return 0;
}
