| Date | November 2007 | Marks available | 2 | Reference code | 07N.1.sl.TZ0.7 |
| Level | SL only | Paper | 1 | Time zone | TZ0 |
| Command term | Write in words | Question number | 7 | Adapted from | N/A |
Question
You may choose from three courses on a lunchtime menu at a restaurant.
s: you choose a salad,
m: you choose a meat dish (main course),
d: you choose a dessert.
You choose a two course meal which must include a main course and either a salad or a dessert, but not both.
Write the sentence above using logic symbols.
Write in words \(s \Rightarrow \neg d\) .
Complete the following truth table.
Markscheme
\(m \wedge (s \underline{\vee} d)\) (A2)
(A1) for \(m \wedge \)
(A1) for \((s\underline{ \vee } d)\)
(A1)(A0) if brackets are missing.
OR
\((m \wedge s) \underline{\vee} (m \wedge d)\) (A2)
(A1) for both brackets correct, (A1) for disjunctive “or” (A1)(A0) if brackets are missing. (C2)
[2 marks]
If you choose a salad then you do not choose a dessert. (A2)
(A1) for “if …then…” (A1) for salad and no dessert in the correct order.
OR
If you choose a salad you do not choose a dessert. (A2) (C2)
[2 marks]
(A1) for each correct column (A1)(A1)(ft) (C2)
[2 marks]
Examiners report
(a) This caused problems for many candidates. They seem to expect to include the implication symbol somewhere.
(b) Most candidates managed to write this correctly.
(c) Not all candidates could complete the truth table correctly. Many managed the first column but then made mistakes in the last column.
