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