Do you think you’re a logical person? If the answer to this question is “Yes”, then try this simple test. We should, however, let you know that 90% of people who try to solve this test come to the wrong conclusion. If you think you’re ready, then let’s start:
Below are four cards. Each card is numbered on one side and has a color on the other side. Your objective is to prove the following statement:
“If a card shows an even number on one face, then its opposite face is blue.”
In order to prove this statement, what is the minimal number of cards you’ll have to flip, and which ones? Take your time to think of the answer, and once you think you're sure, scroll down to see if you're correct.
As the table below shows, you have 16 different options to choose from.
So, you think you've come to the right conclusion? Scroll down to find out.
Answer
The correct answer is: 2 cards - The card with the number 8 digit, and the green card.
The majority of people assume you need to flip number 8 and the blue card, because these are the two cards the question refers to. However, a truly logical thinker would realize that this is incorrect.
The statement in question tells you that when a card has an even number on one face, the other face must be blue.
Therefore, first you need to prove that the back of number 8 is blue – that’s easy enough.
There’s no need to check the blue card, because the statement doesn’t discuss what’s on the other side of blue cards, but rather what’s on the other side of even cards.
Once you check the green card, you can ascertain whether it’s an odd or even number. If the number’s even, then the statement is false.
