#include <bits/stdc++.h>
using namespace std;
int read() {
  bool f = 0;
  int x = 0;
  char c = getchar();
  while (c < '0' || '9' < c) {
    if (c == '-') f = 1;
    c = getchar();
  }
  while ('0' <= c && c <= '9')
    x = (x << 3) + (x << 1) + (c ^ 48), c = getchar();
  return !f ? x : -x;
}
struct node {
  double l, r;
  friend node operator+(node a, node b) {
    node c;
    c.l = a.l * b.l / (1 - a.r * (1 - b.l)),
    c.r = b.r + (1 - b.r) * b.l * a.r / (1 - a.r * (1 - b.l));
    return c;
  }
} tree[5 * 100000 + 5];
double P[100000 + 5], l[5 * 100000 + 5], r[5 * 100000 + 5];
void PushUp(int i) {
  tree[i] = tree[(i << 1)] + tree[(i << 1 | 1)];
  return;
}
void Build(int i, int L, int R) {
  if (L == R) {
    tree[i] = (node){P[L], P[L]};
    return;
  }
  int Mid = (L + R) >> 1;
  Build((i << 1), L, Mid), Build((i << 1 | 1), Mid + 1, R);
  PushUp(i);
  return;
}
void Insert(int i, int L, int R, int p, double x) {
  if (L == R) {
    tree[i] = (node){x, x};
    return;
  }
  int Mid = (L + R) >> 1;
  if (p <= Mid)
    Insert((i << 1), L, Mid, p, x);
  else
    Insert((i << 1 | 1), Mid + 1, R, p, x);
  PushUp(i);
  return;
}
node Query(int i, int L, int R, int qL, int qR) {
  if (qL <= L && R <= qR) return tree[i];
  int Mid = (L + R) >> 1;
  if (qR <= Mid)
    return Query((i << 1), L, Mid, qL, qR);
  else if (Mid + 1 <= qL)
    return Query((i << 1 | 1), Mid + 1, R, qL, qR);
  return Query((i << 1), L, Mid, qL, Mid) +
         Query((i << 1 | 1), Mid + 1, R, Mid + 1, qR);
}
int main() {
  int n = read(), q = read();
  for (int i = 1; i <= n; i++) {
    int a = read(), b = read();
    P[i] = 1.0 * a / b;
  }
  Build(1, 1, n);
  for (int i = 1; i <= q; i++) {
    int opt = read();
    if (opt == 1) {
      int p = read(), a = read(), b = read();
      Insert(1, 1, n, p, 1.0 * a / b);
    } else {
      int l = read(), r = read();
      printf("%.10lf\n", Query(1, 1, n, l, r).l);
    }
  }
  return 0;
}
