# Task 1. (10 points)

Five cards are lying on the table, as shown in the figure.

![](https://cdn.mathpix.com/cropped/2024_05_06_0748dce8a8149f40dec4g-1.jpg?height=211&width=785&top_left_y=971&top_left_x=681)

On each card, there is a letter on one side and a natural number on the other side. Peter said: "If there is a vowel on one side of the card, then there is an even number on the other side of the card." By flipping one card, Katya showed that Peter was wrong. Which card did Katya flip?
# Solution

To prove that Peter is wrong, Katya needs to find a card with an odd number on one side and a vowel on the other. The only card that could have this property is the fourth card, which has the number 7 written on it.

Answer: the fourth card.