Bell-shaped age pyramid represents

Stable population

An age pyramid, also known as a population pyramid, is a graphical representation of the age and sex distribution of a population. It typically consists of three main age groups:

• Pre-reproductive age group: Individuals who are not yet in their reproductive years.
• Reproductive age group: Individuals who are capable of reproduction.
• Post-reproductive age group: Individuals who are beyond their reproductive years.

The shape of the age pyramid provides insights into the growth trends of a population:

• Expanding Population: Characterized by a wide base and a narrow top, indicating a high number of young individuals and a growing population. This shape resembles a triangle.
• Stable Population: Exhibits a bell-shaped or nearly rectangular structure, where the number of individuals in the pre-reproductive and reproductive age groups are approximately equal, suggesting a balanced birth and death rate.
• Declining Population: Shows a narrow base and a wider top, indicating a higher number of older individuals compared to younger ones, reflecting a decreasing population. This shape resembles an inverted triangle or an urn.

Concept in Simple Words:

Imagine a population as a group of people divided into different age categories. If there are many young people and fewer older people, the population is growing, and the age pyramid looks like a triangle. If the number of young and middle-aged people is about the same, and there are fewer older people, the population is stable, and the pyramid looks like a bell. If there are more older people than younger ones, the population is shrinking, and the pyramid looks like an upside-down triangle or an urn.