random number of specific average in c#

i want to generate random numbers between 1 and 5 that their average be one of the number in 1 to 5 that specified by user. for example numbers between 1 to 5 that their avarege be 3. the list length might be change. for example in some cases i want 25 numbers that their average between 1 to 5, in other cases i want 35 numbers that their avarage between 1 to 5. so i want numbers that the avarege be between 1 to 5 that be specified by the user.

i wanna the implementation in c#. i heard thet it could be implement by distributed functions. could you please guide me how?

i see this post but not worked for me.