3. Vasya, Dima, Kolya, and Sergey, who study in grades 5, 6, 7, and 8, decided to form a rock band. Among them, there is a saxophonist, a keyboardist, a drummer, and a guitarist. Vasya plays the saxophone and is not in grade 8. The keyboardist is in grade 6. The drummer is not Dima, Sergey is not the keyboardist and not a student in grade 5. Dima is not in grade 6, and the drummer is not in grade 8. In which grade does Dima study and what instrument does he play?
Answer. Dima studies in the 8th grade and plays the guitar.

Solution. According to the condition, Vasya plays the saxophone, and Dima is not a drummer. But Dima is also not a keyboardist since he does not study in the 6th grade, so he plays the guitar. Since Sergey is not a keyboardist, he is a drummer, and the keyboardist is Kolya. Therefore, Kolya studies in the 6th grade. Sergey does not study in the 5th grade, and since he is a drummer, he is not in the 8th grade either. Thus, he is a 7th grader. Since Vasya does not study in the 8th grade, he is from the 5th grade, and Dima studies in the 8th grade.

Comment. Correct solution - 20 points. Partial justification - 15 points (several tables are considered justification). Only the answer, including the final filled table without explanations of how it was filled - 10 points.

Solution started, with some progress - 5 points. Solution started, but progress is insignificant - 1 point. Correct answer given without explanations - 1 point.