2021HSCMultiple choice
Q9
1 mark
Question
Four cards have either RED or BLACK on one side and either WIN or TRY AGAIN on the other side. The visible cards are: Card 1 WIN; Card 2 BLACK; Card 3 TRY AGAIN; Card 4 RED.
For the statement “If a card is RED, then it has WIN written on the other side.”
What is the minimum number of cards Sam should turn over to check if the statement is true and which cards should be turned over?
A. 1 and 4
B. 3 and 4
C. 1, 2 and 4
D. 1, 3 and 4

Syllabus alignment
Proof
- The Nature of ProofUse formal proof language, contradiction, counter-examples and rigorous arguments involving numbers and inequalities.