Date | May 2015 | Marks available | 2 | Reference code | 15M.1.sl.TZ2.11 |
Level | SL only | Paper | 1 | Time zone | TZ2 |
Command term | Write down | Question number | 11 | Adapted from | N/A |
Question
p:x is a multiple of 12
q:x is a multiple of 6.
Write down in words ¬p.
Write down in symbolic form the compound statement
r: If x is a multiple of 12, then x is a multiple of 6.
Consider the compound statement
s: If x is a multiple of 6, then x is a multiple of 12.
Identify whether s: is the inverse, the converse or the contrapositive of r.
Consider the compound statement
s: If x is a multiple of 6, then x is a multiple of 12.
Determine the validity of s. Justify your decision.
Markscheme
x is not a multiple of 12 (A1) (C1)
p⇒q (A1)(A1)(C2)
Note: Award (A1) for ⇒, (A1) for p and q in the correct order.
Accept q⇐p.
Converse (A1) (C1)
not valid (A1)
for example 18 is a multiple of 6 and not a multiple of 12 (R1) (C2)
Notes: Do not award (A1)(R0). Any multiple of 6 that is not a multiple of 12 can be accepted as a counterexample.