private void hookUp() {
		random = new Random(102405);
		for (Course c : courses) {
			int count = 0;
			while ((count < 20 || random.nextInt(100) < 70) && count < 40) {
				Student s = getRandomItem(students);
				if (!s.getCourses().contains(c)) {
					s.getCourses().add(c);
					count++;
				}
			}
		}
		for (Student s : students) {
			entityManager.merge(s);
		}

	}