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Date November 2016 Marks available 1 Reference code 16N.2.sl.TZ0.2
Level SL only Paper 2 Time zone TZ0
Command term Write down Question number 2 Adapted from N/A

Question

A group of 66 people went on holiday to Hawaii. During their stay, three trips were arranged: a boat trip (\(B\)), a coach trip (\(C\)) and a helicopter trip (\(H\)).

From this group of people:

went on all three trips;
16  went on the coach trip only;
13  went on the boat trip only;
went on the helicopter trip only;
went on the coach trip and the helicopter trip but not the boat trip;
2 went on the boat trip and the helicopter trip but not the coach trip;
4 went on the boat trip and the coach trip but not the helicopter trip;
did not go on any of the trips.

One person in the group is selected at random.

Draw a Venn diagram to represent the given information, using sets labelled \(B\), \(C\) and \(H\).

[5]
a.

Show that \(x = 3\).

[2]
b.

Write down the value of \(n(B \cap C)\).

[1]
c.

Find the probability that this person

(i)     went on at most one trip;

(ii)     went on the coach trip, given that this person also went on both the helicopter trip and the boat trip.

[4]
d.

Markscheme

N16/5/MATSD/SP2/ENG/TZ0/02.a/M     (A5)

 

Notes:     Award (A1) for rectangle and three labelled intersecting circles (U need not be seen),

(A1) for 3 in the correct region,

(A1) for 8 in the correct region,

(A1) for 5, 13 and 16 in the correct regions,

(A1) for \(x\), \(2x\) and \(4x\) in the correct regions.

 

[5 marks]

a.

\(8 + 13 + 16 + 3 + 5 + x + 2x + 4x = 66\)    (M1)

 

Note:     Award (M1) for either a completely correct equation or adding all the terms from their diagram in part (a) and equating to 66.

Award (M0)(A0) if their equation has no \(x\).

 

\(7x = 66 - 45\) OR \(7x + 45 = 66\)     (A1)

 

Note:     Award (A1) for adding their like terms correctly, but only when the solution to their equation is equal to 3 and is consistent with their original equation.

 

\(x = 3\)    (AG)

 

Note:     The conclusion \(x = 3\) must be seen for the (A1) to be awarded.

 

[2 marks]

b.

15     (A1)(ft)

 

Note:     Follow through from part (a). The answer must be an integer.

 

[1 mark]

c.

(i)     \(\frac{{42}}{{66}}{\text{ }}\left( {\frac{7}{{11}},{\text{ }}0.636,{\text{ }}63.6\% } \right)\)     (A1)(ft)(A1)(G2)

 

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

 

(ii)     \(\frac{3}{9}{\text{ }}\left( {\frac{1}{3},{\text{ }}0.333,{\text{ }}33.3\% } \right)\)     (A1)(A1)(ft)(G2)

 

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

 

[4 marks]

d.

Examiners report

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

Syllabus sections

Topic 3 - Logic, sets and probability » 3.7 » Probability of combined events, mutually exclusive events, independent events.
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