World Population

In the context of age-sex pyramids, the shape of the pyramid reflects the birth rates, death rates, and the general demographic make-up of a country. A triangular shaped age-sex pyramid is characteristic of countries with high birth rates and high mortality rates. Generally, these are developing countries where a large portion of the population is young, resulting in a wide base that tapers sharply.

Let’s analyze the options:

• Australia: This country typically has a more evenly distributed age-sex pyramid that is not triangular. Developed nations like Australia often show a column-like or slightly expanding shape due to lower birth rates and longer life expectancies. This suggests more balanced numbers across different age groups rather than the sharp taper found in triangular pyramids.
• Bangladesh: Often displays a triangular pyramid due to higher birth rates and a younger population.
• Nigeria: Similarly, Nigeria frequently shows a triangular shape due to a high proportion of young people, indicative of high birth rates.
• Mexico: While transitioning, Mexico has historically had a triangular age-sex pyramid, although it is gradually evolving to a bell-shaped or barrel-shaped form as birth rates fall and life expectancy increases.

Conclusively, the country whose population does not have a triangular shaped age-sex pyramid is Australia.