To gain a place at a science college, students first have to pass a written test and then a practical test. Each student is allowed a maximum of two attempts at the written test. A student is only allowed a second attempt if they fail the first attempt. No student is allowed more than one attempt at the practical test. If a student fails both attempts at the written test, then they cannot attempt the practical test. The probability that a student will pass the written test at the first attempt is 0.8. If a student fails the first attempt at the written test, the probability that they will pass at the second attempt is 0.6. The probability that a student will pass the practical test is always 0.3.

1. (a)Draw a tree diagram to represent this information, showing the probabilities on the branches.[3]
2. (b)Find the probability that a randomly chosen student will succeed in gaining a place at the college.[2]
3. (c)Find the probability that a randomly chosen student passes the written test at the first attempt given that the student succeeds in gaining a place at the college.[2]

This question uses a diagram from the original paper, which isn't shown here. Open the full paper from the past papers archive to see it.