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Date May 2013 Marks available 3 Reference code 13M.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 : Students stay up late.

q : Students fall asleep in class.

Write the following compound proposition in symbolic form.

If students do not stay up late then they will not fall asleep in class.

[2]
a.

Complete the following truth table.

[3]
b.

Write down a reason why the statement \(\neg ( p \vee \neg q)\) is not a contradiction.

[1]
c.

Markscheme

\(\neg p \Rightarrow \neg q\)     (A1)(A1)     (C2)


Note: Award (A1) for any 2 correct symbols seen in a statement, (A1) for all 3 correct symbols in correct order.

a.

     (A1)(A1)(ft)(A1)(ft)     (C3)


Note: Award (A1) for each correct column. 4th column is follow through from 3rd, 5th column is follow through from 4th.

b.

Not all of last column is F     (R1)(ft)     (C1)


Note: Award (R1)(ft) if final column does not lead to a contradiction.

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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