It used to be 25-54 was the catch all age group for the ideal customer, but as more studies come out, it's become apparent  that the buying habits of a 25 year old are vastly different from a 54 year old. Can you market to both? Yes- if you use a target segmentation marketing plan. We've done that for several clients- like Elliott's Fine Nutrition. A business that sells supplements to people over 50 as well as young women in their 20s is attracting these distinctly different demographics for different reasons. Both are customers, and both need to hear you relating to their needs.