select up.university,qd.difficult_level,round(count(qpd.question_id) / count(distinct(qpd.device_id)),4) as avg_answer_cntfrom question_practice_detail as qpdleft join user_profile as upon up.device_id = qpd.device_idleft join question_detail as qdon qd.question_id = qpd.question_idgroup by universi...