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Date November 2009 Marks available 5 Reference code 09N.1.hl.TZ0.6
Level HL only Paper 1 Time zone TZ0
Command term Find Question number 6 Adapted from N/A

Question

At a nursing college, 80 % of incoming students are female. College records show that 70 % of the incoming females graduate and 90 % of the incoming males graduate. A student who graduates is selected at random. Find the probability that the student is male, giving your answer as a fraction in its lowest terms.

Markscheme

M|G=P(MG)P(G)     (M1)

=0.2×0.90.2×0.9+0.8×0.7     M1A1A1

=0.180.74

=937     A1

[5 marks]

Examiners report

Most candidates answered this question successfully. Some made arithmetic errors.

Syllabus sections

Topic 5 - Core: Statistics and probability » 5.4 » Use of Bayes’ theorem for a maximum of three events.

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