#include <iostream>
#include <sstream>
#include <string>
#include <algorithm>
#include <vector>
#include <stack>
#include <queue>
#include <set>
#include <map>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <cmath>
#include <cassert>
#include <climits>

using namespace std;

#define FOR(i,k,n) for(int i=(k); i<(int)(n); ++i)
#define REP(i,n) FOR(i,0,n)
#define FORIT(i,c) for(__typeof((c).begin())i=(c).begin();i!=(c).end();++i)

template<class T> void debug(T begin, T end){ for(T i = begin; i != end; ++i) cerr<<*i<<" "; cerr<<endl; }
inline bool valid(int x, int y, int W, int H){ return (x >= 0 && y >= 0 && x < W && y < H); }

typedef long long ll;
const int INF = 100000000;
const double EPS = 1e-8;
const int MOD = 1000000007;
int dx[8] = {1, 0, -1, 0, 1, -1, -1, 1};
int dy[8] = {0, 1, 0, -1, 1, 1, -1, -1};
ll gcd(ll a, ll b){
  return (a % b == 0) ? b : gcd(b, a % b);
}

int main(){
  int N;
  ll M;
  while(cin >> N >> M){
    vector<ll> a(N);
    vector<int> p(N);
    REP(i, N) cin >> a[i];
    REP(i, N) cin >> p[i];
    static ll F[1 << 20] = {};
    // 包除原理 (チャレンジブック p.264)
    FOR(S, 1, 1 << N){
      int sign = (__builtin_popcount(S) % 2 == 0) ? -1 : 1;
      ll lcm = 1;
      for (int i = 0; i < N; i++) if(S >> i & 1){
        lcm /= gcd(lcm, a[i]);
        if((double)lcm * a[i] > 1e18){
          lcm = LLONG_MAX;
          break;
        }
        lcm *= a[i];
      }
      F[S] = sign * (M / lcm);
    }
    // 高速ゼータ変換 (http://topcoder.g.hatena.ne.jp/iwiwi/20120422/1335065228)
    REP(i, N)REP(S, 1 << N){
      if(0 == (S & (1 << i))){
        F[S | 1 << i] += F[S];
      }
    }
    double ans = 0;
    REP(S, 1 << N){
      double prob = 1;
      REP(i, N) {
        if(S >> i & 1) prob *= p[i] / 100.0;
        else prob *= (100.0 - p[i]) / 100.0;
      }
      ans += prob * F[S];
    }
    printf("%.8lf\n", ans);
  }
  return 0;
}