Question 1 [15 marks]

An assessment programme for students taking a chemistry module has two components: a written test, and a practical test. 90% of the applicants passed the written test. Among those who passed the written test, 85% passed the practical test. Among those who failed the written test, 40% passed the practical test. The associated probability tree diagram is shown in Figure 1a below.

Pass the practical test 0.85 Pass written test b 0.9 Fail the practical test C Pass the practical test Fail written test d Fail the practical test Figure 1a: Probability tree diagram