Holy Moly! The distribution of "R" and "T" suck with my method! I don't quite understand it because the distribution of "C" is nearly flat as you would expect with random numbers. Here's the test code if you'd like to play...
WITH
cteC AS
( --=== Determine "C"
SELECT CountC = ABS(CHECKSUM(NEWID()))%16+3
FROM dbo.Tally t
WHERE t.N <= 10000
),
cteR AS
( --=== Determine "R" constrained by "C"
SELECT CountC,
CountR = ABS(CHECKSUM(NEWID()))%(25-CountC-6)+3
FROM cteC
),
cteT AS
( --=== Determine "T" constrained by "C" and "R"
SELECT CountC,
CountR,
CountT = 25-CountC-CountR
FROM cteR
) --=== Unpivot the 3 columns of data and do counts of occurances for each Count"x" value.
SELECT unpvt.CountName, unpvt.CountX, COUNT(*) AS Occurances
FROM (
SELECT CountC,CountR,CountT
FROM cteT
) pvt
UNPIVOT (
CountX FOR CountName IN (CountC,CountR,CountT)
)AS unpvt
GROUP BY unpvt.CountName, unpvt.CountX
ORDER BY unpvt.CountName, unpvt.CountX
--Jeff Moden
Change is inevitable... Change for the better is not.