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Date November 2017 Marks available 2 Reference code 17N.1.SL.TZ0.T_7
Level Standard Level Paper Paper 1 Time zone Time zone 0
Command term Determine Question number T_7 Adapted from N/A

Question

Rosewood College has 120 students. The students can join the sports club ( S ) and the music club ( M ).

For a student chosen at random from these 120, the probability that they joined both clubs is 1 4 and the probability that they joined the music club is 1 3 .

There are 20 students that did not join either club.

Complete the Venn diagram for these students.

N17/5/MATSD/SP1/ENG/TZ0/07.a

[2]
a.

One of the students who joined the sports club is chosen at random. Find the probability that this student joined both clubs.

[2]
b.

Determine whether the events S and M are independent.

[2]
c.

Markscheme

* This question is from an exam for a previous syllabus, and may contain minor differences in marking or structure.

N17/5/MATSD/SP1/ENG/TZ0/07.a/M     (A1)(A1)     (C2)

 

Note:     Award (A1) for 30 in correct area, (A1) for 60 and 10 in the correct areas.

 

[2 marks]

a.

30 90   ( 1 3 ,   0.333333 ,   33.3333 % )     (A1)(ft)(A1)(ft)     (C2)

 

Note:     Award (A1)(ft) for correct numerator of 30, (A1)(ft) for correct denominator of 90. Follow through from their Venn diagram.

 

[2 marks]

b.

P ( S ) × P ( M ) = 3 4 × 1 3 = 1 4     (R1)

 

Note:     Award (R1) for multiplying their by 1 3 .

 

therefore the events are independent ( as P ( S M ) = 1 4 )     (A1)(ft)     (C2)

 

Note:     Award (R1)(A1)(ft) for an answer which is consistent with their Venn diagram.

Do not award (R0)(A1)(ft).

Do not award final (A1) if P ( S ) × P ( M ) is not calculated. Follow through from part (a).

 

[2 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 4.6—Combined, mutually exclusive, conditional, independence, prob diagrams
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