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Date May Specimen paper Marks available 3 Reference code SPM.1.SL.TZ0.13
Level Standard Level Paper Paper 1 Time zone Time zone 0
Command term Find Question number 13 Adapted from N/A

Question

Mr Burke teaches a mathematics class with 15 students. In this class there are 6 female students and 9 male students.

Each day Mr Burke randomly chooses one student to answer a homework question.

In the first month, Mr Burke will teach his class 20 times.

Find the probability that on any given day Mr Burke chooses a female student to answer a question.

[1]
a.

Find the probability he will choose a female student 8 times.

[2]
b.

Find the probability he will choose a male student at most 9 times.

[3]
c.

Markscheme

6 15 ( 0.4 , 2 5 )     A1

[1 mark]

a.

P(X = 8)       (M1)

Note: Award (M1) for evidence of recognizing binomial probability. eg P(X = 8), X ∼ B ( 20 , 6 15 ) .

0.180 (0.179705…)    A1

[2 marks]

b.

P(male) =  9 15 ( 0.6 )     A1

P(X ≤ 9) = 0.128 (0.127521…)        (M1)A1

Note: Award (M1) for evidence of correct approach eg, P(X ≤ 9).

[3 marks]

c.

Examiners report

[N/A]
a.
[N/A]
b.
[N/A]
c.

Syllabus sections

Topic 4—Statistics and probability » SL 4.5—Probability concepts, expected numbers
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Topic 4—Statistics and probability » SL 4.8—Binomial distribution
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