4-4. In the box, there are colored pencils.

Vasya said: "There are at least four blue pencils in the box."

Kolya said: "There are at least five green pencils in the box."

Petya said: "There are at least three blue and at least four green pencils in the box."

Misha said: "There are at least four blue and at least four green pencils in the box."

It is known that three of the boys told the truth, and one was wrong. Who was wrong?
Answer: Kolya.

Solution. There should be at least four blue pencils, since otherwise at least two boys - Vasya and Misha - will be wrong. Therefore, all statements about blue pencils are correct.

There should be at least four green pencils, since otherwise three boys - Kolya, Petya, and Misha - will be wrong. There cannot be more than or equal to five, otherwise no one will be wrong, so there are four green pencils, and the one who was wrong is Kolya.