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Date May 2018 Marks available 2 Reference code 18M.1.sl.TZ2.2
Level SL only Paper 1 Time zone TZ2
Command term Complete Question number 2 Adapted from N/A

Question

Consider the following propositions.

p : the baby cries
q : the baby is happy
r : the baby wants to play

Write down, in words, \(\left( {q \wedge r} \right) \Rightarrow \neg p\).

[3]
a.

Complete the following truth table.

[2]
b.

State whether \(\left( {q \wedge r} \right) \Rightarrow \neg p\) is a tautology, contradiction or neither.

[1]
c.

Markscheme

if the baby is happy and wants to play then the baby does not cry     (A1)(A1)(A1) (C3)

Note: Award (A1) for “If… then…”; (A1) for “the baby is happy and wants to play”, (A1) for “the baby does not cry”. Crying must be negated.

[3 marks]

a.

    (A1)(A1) (C2)

Note: Award (A1) for each correct column.

[2 marks]

b.

Neither     (A1)(ft)   (C1)

Note: Follow through from the last column in their part (b).

[1 mark]

c.

Examiners report

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

Syllabus sections

Topic 3 - Logic, sets and probability » 3.3 » Truth tables: concepts of logical contradiction and tautology.
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