#include <bits/stdc++.h>
constexpr int max_n = 1e5;
int main() {
  using namespace std;
  ios_base::sync_with_stdio(false), cin.tie(nullptr);
  cout.precision(10), cout << fixed;
  int n, q;
  cin >> n >> q;
  vector<array<double, 2>> tree(n << 1);
  for (int i = 0, a, b; i < n; ++i) {
    cin >> a >> b;
    tree[i + n] = {1.0 * a / b, 1.0 * a / b};
  }
  auto merge = [&](array<double, 2> a, array<double, 2> b) -> array<double, 2> {
    array<double, 2> res;
    res[0] = a[0] * b[0] / (1 - a[1] * (1 - b[0])),
    res[1] = b[1] + (1 - b[1]) * a[1] * b[0] / (1 - (1 - b[0]) * a[1]);
    return res;
  };
  for (int i = n - 1; i; --i) {
    tree[i] = merge(tree[i << 1], tree[i << 1 | 1]);
  }
  while (q--) {
    int type;
    cin >> type;
    if (type == 1) {
      int i, a, b;
      cin >> i >> a >> b;
      i += n - 1, tree[i][0] = tree[i][1] = 1.0 * a / b;
      for (i >>= 1; i; i >>= 1) tree[i] = merge(tree[i << 1], tree[i << 1 | 1]);
      continue;
    }
    int l, r;
    cin >> l >> r;
    array<double, 2> a = {1, 0}, b = {1, 0};
    for (l += n - 1, r += n; l < r; l >>= 1, r >>= 1) {
      if (l & 1) a = merge(a, tree[l++]);
      if (r & 1) b = merge(tree[--r], b);
    }
    cout << merge(a, b)[0] << '\n';
  }
}
