#include <bits/stdc++.h>
using namespace std;
const int maxn = 1e5 + 15;
const int mod = 1e9 + 7;
const int inf = 0x3f3f3f3f;
int n, m;
double a[maxn * 4], b[maxn * 4];
double q[maxn * 4];
inline void push_up(int u) {
  a[u] = a[(u << 1)] * a[(u << 1 | 1)];
  b[u] = b[(u << 1)] + b[(u << 1 | 1)] * a[(u << 1)];
}
void build(int u, int l, int r) {
  if (l == r) {
    a[u] = q[l];
    b[u] = q[l];
    return;
  }
  int mid = (l + r) >> 1;
  build((u << 1), l, mid);
  build((u << 1 | 1), mid + 1, r);
  push_up(u);
}
void upd(int u, int l, int r, int x, double cc) {
  if (l == r) {
    a[u] = b[u] = cc;
    return;
  }
  int mid = (l + r) >> 1;
  if (x <= mid)
    upd((u << 1), l, mid, x, cc);
  else
    upd((u << 1 | 1), mid + 1, r, x, cc);
  push_up(u);
}
pair<double, double> query(int u, int l, int r, int ql, int qr) {
  if (ql <= l && r <= qr) {
    return make_pair(a[u], b[u]);
  }
  int mid = (l + r) >> 1;
  if (qr <= mid)
    return query((u << 1), l, mid, ql, qr);
  else if (ql > mid)
    return query((u << 1 | 1), mid + 1, r, ql, qr);
  else {
    pair<double, double> lef = query((u << 1), l, mid, ql, qr);
    pair<double, double> rig = query((u << 1 | 1), mid + 1, r, ql, qr);
    pair<double, double> ret;
    ret.second = lef.second + rig.second * lef.first;
    ret.first = lef.first * rig.first;
    return ret;
  }
}
int main() {
  scanf("%d%d", &n, &m);
  for (int i = 1, a, b; i <= n; i++) {
    scanf("%d%d", &a, &b);
    double pp = double(a) / b;
    q[i] = (1 - pp) / pp;
  }
  build(1, 1, n);
  while (m--) {
    int op, x, y, z;
    scanf("%d", &op);
    if (op == 1) {
      scanf("%d%d%d", &x, &y, &z);
      double pp = double(y) / z;
      q[x] = (1 - pp) / pp;
      upd(1, 1, n, x, q[x]);
    } else {
      scanf("%d%d", &x, &y);
      printf("%.10f\n", 1.0 / (query(1, 1, n, x, y).second + 1));
    }
  }
  return 0;
}
