








A set of four 3x5 cards is dealt on a
table



as shown above.
Each card has a letter



on one side and a
number on the other.



The dealer proposes that these 4 cards
satisfy the rule:



“If there is a vowel on one side of the
card,



then
there is an odd number on the other.”



What is the smallest number of cards you
have to turn



over to be sure
the rule is satisfied? Which ones?

