-- based on your median query 
SELECT T1.ST,
       (SELECT ((SELECT MAX(H1.NUM)
                   FROM (SELECT TOP 50 PERCENT T2.NUM
                           FROM dbo.t AS T2
                          WHERE T2.ST = T1.ST
                          ORDER BY T2.NUM ASC) AS H1) +
                (SELECT MIN(H2.NUM)
                   FROM (SELECT TOP 50 PERCENT T3.NUM
                           FROM dbo.t AS T3
                          WHERE T3.ST = T1.ST
                          ORDER BY T3.NUM DESC) AS H2)) / CONVERT(DECIMAL(10, 2), 2)) AS Median
  FROM (SELECT DISTINCT T.ST
          FROM dbo.t AS T) AS T1;

-- another approach
SELECT T1.ST,
       (SELECT SUM(T2.NUM) / CAST(CASE WHEN cnt % 2 = 0 THEN 2 ELSE 1 END AS DECIMAL(10, 2))
          FROM (SELECT TOP(CASE WHEN cnt % 2 = 0 THEN 2 ELSE 1 END) T2.NUM
                  FROM (SELECT TOP(cnt / 2 + 1) T2.NUM
                          FROM dbo.t AS T2
                         WHERE T2.ST = T1.ST
                         ORDER BY T2.NUM) AS T2
                 ORDER BY T2.NUM DESC) AS T2) AS Median
  FROM (SELECT T.ST, COUNT(T.NUM) AS cnt
          FROM dbo.t AS T
         GROUP BY T.ST) AS T1