What type of population pyramid would a nation most likely have if it had a high birth rate 30 years ago and has a low birth rate now?
constrictive
improving
stationary
expansive
A nation that had a high birth rate 30 years ago and has a low birth rate now would most likely have a constrictive population pyramid.
To determine the type of population pyramid a nation would have based on its birth rate patterns, we need to understand how birth rates affect the population structure.
A population pyramid is a graphical representation of a population's age and gender distribution. It is typically divided into different age groups, with males displayed on one side and females on the other. The width of each age group indicates the proportion of individuals within that age range, and the vertical axis represents the population size.
In this case, if a nation had a high birth rate 30 years ago and now has a low birth rate, we can expect the population pyramid to have certain characteristics.
1. Constrictive Population Pyramid: A constrictive population pyramid is characterized by a narrow base, indicating a low proportion of young individuals, and a wider top, representing a higher proportion of older individuals. The high birth rate 30 years ago would have resulted in a large young population at that time. However, the subsequent low birth rate would have reduced the number of new births, resulting in a decline in the number of young individuals and a smaller base in the present population pyramid.
2. Improving Population Pyramid: An improving population pyramid shows a gradually narrowing structure, with a decreasing proportion of young individuals but still a significant number in the younger age groups. Although the birth rate has decreased, if it is still relatively higher than the death rate, there will still be a substantial population of young individuals, despite a decline compared to 30 years ago.
3. Stationary Population Pyramid: A stationary population pyramid would display relatively equal proportions across different age groups, indicating a nearly constant population size for each age cohort over time. This situation occurs when the birth rate and death rate are in balance. If the nation's birth rate has decreased to match the low death rate, there would not be a significant change in the population distribution across age groups.
4. Expansive Population Pyramid: An expansive population pyramid features a wide base, reflecting a high proportion of young individuals in the population. However, since the birth rate has decreased, it is less likely for a nation with a low birth rate now to have an expansive population pyramid, as it would indicate a continued high birth rate and a growing young population.
Considering the given information of a high birth rate 30 years ago and a low birth rate now, the most likely population pyramid would be a constrictive population pyramid. This is because the high birth rate would have resulted in a large population of young individuals 30 years ago. However, the subsequent low birth rate would have reduced the number of new births, leading to a decline in the proportion of young individuals in the present population pyramid and a narrower base.