#include <cmath>
#include <iomanip>
#include <iostream>
using namespace std;
int n, p[22]; long long m, a[22], d[1048588];
long long gcd(long long x, long long y) {
	if (y == 0) return x;
	return gcd(y, x % y);
}
int main() {
	cin >> n >> m;
	for (int i = 0; i < n; i++) cin >> a[i];
	for (int i = 0; i < n; i++) cin >> p[i];
	d[0] = 1;
	double v = log10(m);
	for (int i = 0; i < n; i++) {
		for (int j = 1 << i; j < 2 << i; j++) {
			long long g = gcd(d[j - (1 << i)], a[i]);
			d[j] = d[j - (1 << i)] / g;
			if (log10(d[j]) + log10(a[i]) >= v + 0.01) d[j] = m + 1;
			else d[j] *= a[i];
		}
	}
	for (int i = 0; i < 1 << n; i++) d[i] = m / d[i];
	for (int i = 0; i < n; i++) {
		for (int j = 0; j < 1 << n; j++) {
			if ((j >> i) & 1) d[j] -= d[j - (1 << i)];
		}
	}
	double ex = 0.0;
	for (int i = 0; i < 1 << n; i++) {
		double prob = 1.0;
		for (int j = 0; j < n; j++) {
			prob *= 0.01 * ((i >> j) & 1 ? p[j] : 100 - p[j]);
		}
		ex += prob * (m - abs(d[i]));
	}
	cout << fixed << setprecision(15) << ex << endl;
	return 0;
}
