Selecting subgroup with given mean and standard dev. below given value


New Member
I have a group of subjects with variable age and I would like to select a sub-group with given number of subjects where all selected subjects have age in the given range and the mean of the sub-group equals M, which is the middle of the range. Moreover, the standard deviation of the sub-group should be below a known value. What would be the best algorithm to make the selection?
For Ex: select 25 subjects with age in the range of 10-30 years having the mean age of 20 years and standard dev from the mean below 5years. The original group has 500 subjects in the age ranging 5-70y.
Thank you a lot for help.