(i)[2]
Draw a tree diagram that is fully labelled so that every outcome is shown.
(ii)[4]
If a student obtains the certificate, determine the probability that this student failed the test on the first attempt.
Mathematics 9709 · AS & A Level · The Poisson distribution
The Poisson distribution — practice question
At the end of a mathematics revision course, students must take a test in order to receive a certificate. The chance that any student passes the test on the first try is $0.85$. Students who do not pass are permitted one more attempt, and the probability that any student passes the retake is $0.65$.