The age composition of a population refers to the number of people in different age groups in a country. The population of a nation is generally grouped into three broad categories .
( a ) Children ( generally below 15 years ) They are economically unproductive and need to be provided with food , clothing , education and medical care.
( b ) Working Age ( 15 - 59 years ) They are economically productive and biological by reproductive . They comprise the working population .
( c ) Aged ( above 59 years ) They can be economically productive though they may have retired . They may be working voluntarily but they are not available for employment through recruitment .
The percentage of children and the aged affect the dependency ratio because these groups are not productive.