| Date | May Specimen | Marks available | 2 | Reference code | SPM.1.sl.TZ0.10 |
| Level | SL only | Paper | 1 | Time zone | TZ0 |
| Command term | Write down | 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, \(s \Rightarrow q\) .
Write down in words, the inverse of the statement, \(s \Rightarrow q\) .
Determine the validity of the argument in (b). Give a reason for your decision.
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.
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.
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.
