Q:

Selecting from a list returned by Tuples

Select[Tuples[{1, 1/2}, {4, 4}], Total [#] == 15]

I want to select all tuples in the result returned by Tuples that have total of their elements equal to 15. The answer I got was only {}. Why?

A:

There was an excelent answer with an illustration, but I would like to point out the specific mistakes:

Pure function in the second argmuent should end with &
Total[#] by default only sums on the first level, but you need more.

