#include <bits/stdc++.h>
using namespace std;
const int N = 1e5 + 5;
struct node {
  double a, b;
  node() {}
  node(double a, double b) : a(a), b(b) {}
};
double val[N];
double A[N << 2], B[N << 2];
void PushUp(int rt) {
  A[rt] =
      A[rt << 1] * A[rt << 1 | 1] / (1.0 - (1.0 - A[rt << 1 | 1]) * B[rt << 1]);
  B[rt] = B[rt << 1 | 1] + A[rt << 1 | 1] * (1.0 - B[rt << 1 | 1]) *
                               B[rt << 1] /
                               (1.0 - (1.0 - A[rt << 1 | 1]) * B[rt << 1]);
}
void build(int l, int r, int rt) {
  if (l == r) {
    A[rt] = val[l];
    B[rt] = val[l];
    return;
  }
  int m = (l + r) >> 1;
  build(l, m, rt << 1);
  build(m + 1, r, rt << 1 | 1);
  PushUp(rt);
}
void update(int pos, double x, int l, int r, int rt) {
  if (l == r) {
    A[rt] = x;
    B[rt] = x;
    return;
  }
  int m = (l + r) >> 1;
  if (pos <= m)
    update(pos, x, l, m, rt << 1);
  else
    update(pos, x, m + 1, r, rt << 1 | 1);
  PushUp(rt);
}
node query(int L, int R, int l, int r, int rt) {
  if (L <= l && r <= R) return node(A[rt], B[rt]);
  int m = (l + r) >> 1;
  double a, b;
  if (m < L) return query(L, R, m + 1, r, rt << 1 | 1);
  if (m >= R) return query(L, R, l, m, rt << 1);
  node t1 = query(L, R, l, m, rt << 1);
  node t2 = query(L, R, m + 1, r, rt << 1 | 1);
  a = t1.a * t2.a / (1.0 - (1.0 - t2.a) * t1.b);
  b = t2.b + t2.a * (1.0 - t2.b) * t1.b / (1.0 - (1.0 - t2.a) * t1.b);
  return node(a, b);
}
int main() {
  int n, m;
  while (~scanf("%d%d", &n, &m)) {
    for (int i = 1; i <= n; i++) {
      int a, b;
      scanf("%d%d", &a, &b);
      val[i] = 1.0 * a / b;
    }
    build(1, n, 1);
    while (m--) {
      int id;
      scanf("%d", &id);
      if (id == 1) {
        int i, a, b;
        scanf("%d%d%d", &i, &a, &b);
        update(i, 1.0 * a / b, 1, n, 1);
      } else {
        int a, b;
        scanf("%d%d", &a, &b);
        printf("%.10f\n", query(a, b, 1, n, 1).a);
      }
    }
  }
  return 0;
}
