User interface language: English | Español

Date November 2017 Marks available 4 Reference code 17N.3srg.hl.TZ0.2
Level HL only Paper Paper 3 Sets, relations and groups Time zone TZ0
Command term Verify Question number 2 Adapted from N/A

Question

\(A\), \(B\) and \(C\) are three subsets of a universal set.

Consider the sets \(P = \{ 1,{\text{ }}2,{\text{ }}3\} ,{\text{ }}Q = \{ 2,{\text{ }}3,{\text{ }}4\} \) and \(R = \{ 1,{\text{ }}3,{\text{ }}5\} \).

Represent the following set on a Venn diagram,

\(A\Delta B\), the symmetric difference of the sets \(A\) and \(B\);

[1]
a.i.

Represent the following set on a Venn diagram,

\(A \cap (B \cup C)\).

[1]
a.ii.

For sets \(P\), \(Q\) and \(R\), verify that \(P \cup (Q\Delta R) \ne (P \cup Q)\Delta (P \cup R)\).

[4]
b.i.

In the context of the distributive law, describe what the result in part (b)(i) illustrates.

[2]
b.ii.

Markscheme

N17/5/MATHL/HP3/ENG/TZ0/SG/M/02.a.i     A1

[1 mark]

 

Note: Accept alternative set configurations

a.i.

N17/5/MATHL/HP3/ENG/TZ0/SG/M/02.a.ii     A1

 

Note:     Accept alternative set configurations.

 

[1 mark]

a.ii.

LHS:

\(Q\Delta R = \{ 1,{\text{ }}2,{\text{ }}4,{\text{ }}5\} \)     (A1)

\(P \cup (Q\Delta R) = \{ 1,{\text{ }}2,{\text{ }}3,{\text{ }}4,{\text{ }}5\} \)     A1

RHS:

\(P \cup Q = \{ 1,{\text{ }}2,{\text{ }}3,{\text{ }}4\} \) and \(P \cup R = \{ 1,{\text{ }}2,{\text{ }}3,{\text{ }}5\} \)     (A1)

\((P \cup Q)\Delta (P \cup R) = \{ 4,{\text{ }}5\} \)     A1

hence \(P \cup (Q\Delta R) \ne (P \cup Q)\Delta (P \cup R)\)     AG

 

[4 marks]

b.i.

the result shows that union is not distributive over symmetric difference     A1R1

 

Notes:     Award A1 for “union is not distributive” and R1 for “over symmetric difference”. Condone use of \( \cup \) and \(\Delta \).

 

[2 marks]

b.ii.

Examiners report

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

Syllabus sections

Topic 8 - Option: Sets, relations and groups » 8.1 » Finite and infinite sets. Subsets.

View options