Question

What is the difference between a decreasing population and a decreasing rate of population growth?

Answer 1

Population:

As per Merriam- Webster Dictionary, Population is the whole number of people or inhabitants in a country or region.

For example: Consider the popuation of Humans in the Following city A

Year	Population
2015	2.0 Lacs
2016	2.5 Lacs
2017	1.8 Lacs

Decreasing Population:

When the population of a certain region gets reduced. It may happen due to several factors including sub-replacement fertility (along with limited immigration), heavy emigration, disease, famine, war & decrease in birth rate.

In above Example, the popualation of city A was 2.5 Lacs in year 2016 but it reduced to 1.8 Lacs in year 2017.

this reduction = 2.5 Lacs - 1.8 Lacs = 0.7 Lacs

So, the population of City A reduced by 0.7 Lacs in year 2017.

Population Growth rate (PGR) :

It is the ratio of difference between present & past value of population to past value for given time period.

Population Growth rate =

Here N is the time period.

For above Example, Population Growth rate for year 2015 to 2016,

PGR =

So, PGR = +25 %

For above Example, Population Growth rate for year 2016 to 2017,

PGR =

So, PGR = -28 %

Now we can see that popualation growth rate has decreased from +25% in 2016 to -28% in 2017.

So, decreasing rate of popualation growth =

So, decreasing rate of popualation growth = -2.12

if this value is poitive then it is  Increasing rate of popualation growth.