(i) Population composition refers to those characteristics of population which are measurable and helps in distinguishing one group of people from other such as age, sex, literacy rate, occupation etc.
(ii) Age structure represents the number of people of different age groups. It is an important indicator of population composition, since a large size of population in the age group of 15- 59 indicates a large working population.
(iii) The ratio between the number of women and men in the population is called the Sex Ratio. In some countries it is calculated by using the formula:
Male population/Female Population x 1000 or the number of males per thousand females. In India, Female population/Male Population x 1000 or the number of females per thousand males.