jmc

Five cards are lying on a table as shown. $$\begin{array}{ccccc}& & \boxed{\mathtt{P}}& & \boxed{\mathtt{Q}}\\ & & & & \\ \boxed{3}& & \boxed{4}& & \boxed{6}\end{array}$$ Each card has a letter on one side and a whole number on the other side. Jane said, "If a vowel is on one side of any card, then an even number is on the other side." Mary showed Jane was wrong by turning over one card. Which card did Mary turn over? (Each card number is the one with the number on it. For example card 4 is the one with 4 on it, not the fourth card from the left/right)