(a) A population at any given time is composed of individuals ages. If the age distribution (per cent individuals of a given age or age group) is plotted for these population, the resulting structure is called an age pyramid.
(b) Age distribution depends upon the natality and mortality and determines the population growth. With regard to age distribution, there are three kinds of population.
1. Rapidly growing or expanding population : It has high birth rate and low rate, so there are more number of young individuals in the population. According to a recent survey, more than 36% of the Indian population consists of *** below the age of 14 years, so the Indian population is called young population.
2. Stationary or stable population : It has equal birth and ***** rates, so the population shows zero population growth.
3. Declining population : It has higher ***** rate than birth rate, so the population of young members is lower than that of old members, e.g.,Japan (ageing population)
