When discussing human population trends,birth rate is often expressed as a number called the total fertility rate (TFR).The TFR is the number of children an average woman in the country has in her lifetime.The number of children a couple must have to replace themselves in the population is called the total replacement rate (TRR).TRR can be used a lot like death rate when calculating population trends.As a worldwide average,each couple must have 2.1 children to replace themselves (the extra 0.1 is the result of infant mortality).
TFR and TRR are given below for several countries.Which country has a decreasing population size?

Question

Quizplus · Accepted Answer

In order for a population to maintain its size, the TRR needs to be at least 2.1. A TRR of less than 2.1 indicates that the population is decreasing, and a TRR greater than 2.1 indicates that the population is increasing.

The only country among the choices with a TRR less than 2.1 is D, with a TFR of 7 and TRR of 9. This indicates that the population is growing, but at a decreasing rate. The high TFR and TRR suggest that the population is growing rapidly, but this growth rate is not sustainable and will eventually lead to a decrease in population size.

When Discussing Human Population Trends,birth Rate Is Often Expressed as a Number