Question

From 1980-1990, the population of a country was increased by 20%. From 1990-2000, the population of the country was increased by 20%. From 2000-2010, the population of the country was increased by 20%. Population (in percentage) of the country from 1980-2010 was increase by

please I need a good step by step explanation I try to resolved it but I can't do it​

Answer 1

The % of the increase in population from 1980 to 2000 will be 72.8%

Explanation:

Let the population in the year of 1980 was x.

If the population from 1980 to 1990 has increased by 20%, then the population in the year 1990 will be
`x(1 + (20)/(100)) = 1.2x`.

Now, from 1990 to 2000, the population has again increased by 20%.

So, the population in the year 2000 will be
`1.2x(1 + (20)/(100)) = 1.44x`.

Again, from 2000 to 2010, the population has increased by 20%.

Therefore, the population in the year 2010 will be
`1.44x(1 + (20)/(100)) = 1.728x`.

Now, the population increased from x to 1.728x between the years 1980 to 2010.

Hence, the % of the increase in population from 1980 to 2000 will be
`((1.728x - x)/(x)) * 100\% = 72.8\%` (Answer)