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Date May Specimen paper Marks available 2 Reference code SPM.1.AHL.TZ0.17
Level Additional Higher Level Paper Paper 1 Time zone Time zone 0
Command term Find Question number 17 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 he will choose a female student 8 times.

[2]
a.

The Head of Year, Mrs Smith, decides to select a student at random from the year group to read the notices in assembly. There are 80 students in total in the year group. Mrs Smith calculates the probability of picking a male student 8 times in the first 20 assemblies is 0.153357 correct to 6 decimal places.

Find the number of male students in the year group.

[4]
b.

Markscheme

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]

a.

let x be the number of male students

recognize that probability of selecting a male is equal to  x 80        (A1)

( set up equation 20 C 8 ( x 80 ) 8 ( 80 x 80 ) 12 = ) 0.153357           (M1)

number of male students = 37         (M1)A1

Note: Award (M1)A0 for 27.

[4 marks]

b.

Examiners report

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

Syllabus sections

Topic 4—Statistics and probability » SL 4.8—Binomial distribution
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Topic 4—Statistics and probability

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