Which of the following must be true about the mean age, m, of the combined group of men and women at the retirement home?
1) The mean age of the combined group is equal to the mean age of the men.
2) The mean age of the combined group is equal to the mean age of the women.
3) The mean age of the combined group is equal to the sum of the mean ages of the men and women.
4) The mean age of the combined group is greater than the mean age of the men and women individually.
