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Date May Specimen Marks available 2 Reference code SPM.1.sl.TZ0.10
Level SL only Paper 1 Time zone TZ0
Command term State Question number 10 Adapted from N/A

Question

Consider the following statements about the quadrilateral ABCD

\(q:\) ABCD has four equal sides     \(s:\) ABCD is a square

Express in words the statement, \(s \Rightarrow q\) .

[2]
a.

Write down in words, the inverse of the statement, \(s \Rightarrow q\) .

[2]
b.

Determine the validity of the argument in (b). Give a reason for your decision.

[2]
c.

Markscheme

If ABCD is a square, then ABCD has four equal sides.     (A1)(A1)     (C2)


Note: Award (A1) for if… then, (A1) for propositions in the correct order.

a.

If ABCD is not a square, then ABCD does not have four equal sides.     (A1)(A1)     (C2)

 

Note: Award (A1) for if… then, (A1) for propositions in the correct order.

b.

Not a valid argument. ABCD may have 4 equal sides but will not necessarily be a square. (It may be a rhombus)     (A1)(R1)     (C2)

 

Note: Award (R1) for correct reasoning, award (A1) for a consistent conclusion with their answer in part (b).

It is therefore possible that (R1)(A0) may be awarded, but (R0)(A1) can never be awarded.

 

Note: Simple examples of determining the validity of an argument without the use of a truth table may be tested.

c.

Examiners report

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

Syllabus sections

Topic 3 - Logic, sets and probability » 3.2 » Compound statements: implication, \( \Rightarrow \) ; equivalence, \( \Leftrightarrow \) ; negation, \(\neg \) ; conjunction, \( \wedge \) ; disjunction, \( \vee \) ; exclusive disjunction, \(\underline \vee \) .
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