#include <bits/stdc++.h>
using namespace std;
const int NMAX = 270000;
struct Node {
  double LL, LR, RL, RR;
};
int N, Q;
int L;
Node tree[NMAX];
Node merge(const Node &l, const Node &r) {
  double t1, t2;
  t1 = l.LL + l.LR * r.LL * l.RL * 1 / (1 - l.RR * r.LL);
  t2 = r.RR + r.RL * l.RR * r.LR * 1 / (1 - r.LL * l.RR);
  return (Node){t1, 1 - t1, 1 - t2, t2};
}
void buildTree() {
  int pos;
  for (pos = L - 1; pos; pos -= 1)
    tree[pos] = merge(tree[2 * pos], tree[2 * pos + 1]);
}
void edit(int pos, double v) {
  pos += L - 1;
  tree[pos] = (Node){1 - v, v, 1 - v, v};
  for (pos >>= 1; pos; pos >>= 1)
    tree[pos] = merge(tree[2 * pos], tree[2 * pos + 1]);
}
Node query(int pos, int l, int r, int p, int q) {
  int mid = (l + r) >> 1;
  Node resl, resr;
  if (l == p && r == q) return tree[pos];
  if (p <= mid) resl = query(2 * pos, l, mid, p, min(q, mid));
  if (q > mid) resr = query(2 * pos + 1, mid + 1, r, max(p, mid + 1), q);
  if (p <= mid && q > mid)
    return merge(resl, resr);
  else if (p <= mid)
    return resl;
  return resr;
}
int main() {
  int i, t, pos, x, y;
  scanf("%d %d", &N, &Q);
  for (L = 1; L < N; L <<= 1)
    ;
  for (i = 1; i <= N; i += 1) {
    scanf("%d %d", &x, &y);
    tree[L + i - 1] = (Node){1 - (double)x / y, (double)x / y,
                             1 - (double)x / y, (double)x / y};
  }
  for (; i <= L; i += 1) tree[L + i - 1] = (Node){0.5, 0.5, 0.5, 0.5};
  buildTree();
  for (i = 1; i <= Q; i += 1) {
    scanf("%d", &t);
    if (t == 1) {
      scanf("%d %d %d", &pos, &x, &y);
      edit(pos, (double)x / y);
    } else {
      scanf("%d %d", &x, &y);
      printf("%.10f\n", query(1, 1, L, x, y).LR);
    }
  }
  exit(0);
}
