select u.university,qd.difficult_level, round(count(q.device_id) /count(distinct q.device_id) ,4)as avg_answer_cnt from user_profile as u join question_practice_detail as q on u.device_id = q.device_id join question_detail as qd on q.question_id = qd.question_id GROUP BY university,qd.difficult_leve...