[填空题]
Jennifer is about to take three exams in ordk efpj) x3cu82v s r7a)wqu)y(er: Mathe0 8se*/twjwoz klfj39 matics, Chemistry and Biology. Based on what she has learned and practiced, she estimates that the probabilities that she will pass Mathematics, Chemistry and Biology exams are 0.8,0.6 and 0.7 , respectively. Assuming that the probability of Jenifer being passing an exam is independent of the o9/ esf*0t8wjjl3 owkzthers, find the probability that
1. she will pass all three exams;
2. she will pass only one of the exams;
3. she will pass the last two exams given that she doesn't pass the first exam;
4. she will pass at least one exam.
