Below 15 years of age, an individual is too young to take care of herself/himself and is therefore incapable of working for an income, and is totally dependent on their parents. Above 59 years of age is assumed as the standard upper limit when health concerns get ahead of productivity, and so one becomes dependent on others for care and support. The ages 15 to 59 are considered as prime working age group as they are not dependent on any other group, and could earn to make a living without any serious hurdles.