SELECT `stud`.`Name`
FROM `stud`
INNER JOIN
(SELECT AVG(`stud`.`E1` + `stud`.`E2` + `stud`.`E3`) / 3 AS average
FROM `stud`
INNER JOIN `rob_gurt`
ON `rob_gurt`.`NumS` = `stud`.`NumS`
INNER JOIN `gurt`
ON `gurt`.`NumG` = `rob_gurt`.`NumG`
WHERE `gurt`.`NameG` = "Музыкальный") AS q
ON `stud`.`E1` <= q.average