| Date | May 2014 | Marks available | 2 | Reference code | 14M.1.sl.TZ2.2 |
| Level | SL only | Paper | 1 | Time zone | TZ2 |
| Command term | Write down | Question number | 2 | Adapted from | N/A |
Question
Two propositions \(p\) and \(q\) are defined as follows
\(p\): Eva is on a diet
\(q\): Eva is losing weight.
Write down the following statement in words.
\[q \Rightarrow p\]
Write down, in words, the contrapositive statement of \(q \Rightarrow p\).
Determine whether your statement in part (a) is logically equivalent to your statement in part (b). Justify your answer.
Markscheme
If Eva is losing weight then Eva is on a diet (A1)(A1) (C2)
Notes: Award (A1) for If… then…
For Spanish candidates, only accept “Si” and “entonces”.
For French candidates, only accept “Si” and “alors”.
For all 3 languages these words are from the subject guide.
Award (A1) for correct propositions in correct order.
[2 marks]
If Eva is not on a diet then she is not losing weight (A1)(A1) (C2)
Notes: Award (A1) for “not on a diet” and “not losing weight” seen, (A1) for complete correct answer.
No follow through from part (a).
[2 marks]
The statements are logically equivalent (A1)(ft)
The contrapositive is always logically equivalent to the original statement (R1)(ft)
OR
A correct truth table showing the equivalence (R1)(ft) (C2)
Note: Follow through from their answers to part (a) and part (b).
[2 marks]
