WITH t AS
(
SELECT LEVEL id
     , 100 - CEIL(LEVEL/8) score
     , '수학'  gwamok
     , '1학기' hakgi
     , '중간'  gubun
  FROM dual
 CONNECT BY LEVEL <= 100
)
SELECT gwamok, hakgi, gubun
     , id, score
     , rk
     , rk2
     , rat
     , CASE WHEN              rat <=  4 THEN 1
            WHEN rat >  4 AND rat <= 11 THEN 2
            WHEN rat > 11 AND rat <= 23 THEN 3
            WHEN rat > 23 AND rat <= 40 THEN 4
            WHEN rat > 40 AND rat <= 60 THEN 5
            WHEN rat > 60 AND rat <= 77 THEN 6
            WHEN rat > 77 AND rat <= 89 THEN 7
            WHEN rat > 89 AND rat <= 96 THEN 8
            WHEN rat > 96               THEN 9
        END grd
  FROM (SELECT gwamok, hakgi, gubun
             , id, score
             , rk
             , (rk + (cnt - 1) / 2) rk2
             , (rk + (cnt - 1) / 2) / tot * 100 rat
          FROM (SELECT gwamok, hakgi, gubun
                     , id, score
                     , RANK() OVER(PARTITION BY gwamok, hakgi, gubun ORDER BY score DESC) rk
                     , COUNT(*) OVER(PARTITION BY gwamok, hakgi, gubun, score) cnt
                     , COUNT(*) OVER(PARTITION BY gwamok, hakgi, gubun) tot
                  FROM t
                )
        )
;

with 부분은 테스트 샘플 만드는 쿼리이니 신경 안쓰셔도 됩니다.
분석함수 OVER 부분이 없으면 쿼리가 복잡해집니다.
요구조건이 좀더 명확해야 할 것 같습니다.
조건 없이 전체 조회해야 하나요?
아니면 특정 조건 걸고 조회하나요?

SELECT id
     , gwamok, hakgi, gubun
     , score
     , avg_score
     , rk
     , rk2
     , rat
     , CASE WHEN              rat <=  4 THEN 1
            WHEN rat >  4 AND rat <= 11 THEN 2
            WHEN rat > 11 AND rat <= 23 THEN 3
            WHEN rat > 23 AND rat <= 40 THEN 4
            WHEN rat > 40 AND rat <= 60 THEN 5
            WHEN rat > 60 AND rat <= 77 THEN 6
            WHEN rat > 77 AND rat <= 89 THEN 7
            WHEN rat > 89 AND rat <= 96 THEN 8
            WHEN rat > 96               THEN 9
        END grd
  FROM (SELECT id
             , gwamok, hakgi, gubun
             , score
             , avg_score
             , rk
             , (rk + (cnt - 1) / 2) rk2
             , (rk + (cnt - 1) / 2) / tot * 100 rat
          FROM (SELECT a.id
                     , a.gwamok, a.hakgi, a.gubun
                     , a.score
                     , AVG(b.score) avg_score
                     , COUNT(CASE WHEN a.score < b.score THEN 1 END) + 1 rk
                     , COUNT(CASE WHEN a.score = b.score THEN 1 END)     cnt
                     , COUNT(*) tot
                  FROM t a
                 INNER JOIN t b
                    ON a.gwamok = b.gwamok
                   AND a.hakgi  = b.hakgi 
                   AND a.gubun  = b.gubun 
                 WHERE a.id     = :v_id
                   AND a.hakgi LIKE CONCAT(:v_hakgi, '%')
                   AND a.gubun LIKE CONCAT(:v_gubun, '%')
                 GROUP BY a.id, a.gwamok, a.hakgi, a.gubun, a.score
                ) a
        ) a
;