This is a puzzle from brilliant.org - a website dedicated to helping people learn more effectively through conceptual quizzes. When the website first had this puzzle published about 75% of the people who tried to figure it out got it wrong.
We have three boxes.
Only one of the boxes has a car inside.
Under each box there is a ststement.
Only one of the three statements is true.
Which one of the three boxes has a car inside?
Here is the solution to the puzzle in case you haven't figured it out or you just want to confirm you got it right:
If the car is in box one then both the statements below box one and box three would be true, but the puzzle says only one of the three statements can be true. So the car is not in box one.
If the car is in box three then both the statements below boxes two and three would both be true. Again only one of the three statements can be true. So the car is not in box three.
We are left with box two. The car has to be in box two. The one true statement is the one under box three: "the car isn not in box 1".