The population of a village increases at the rate of 25 per thousand annually. If thepresent population is 84050, what was the population two years ago?

Correct option is D

Given:

Present population = 84050

Annual increase rate =$$\frac{25}{1000}$$​ = 0.025 or 2.5%

Time = 2 years

Formula Used:

Present Population = $$\text{Past Population} \times \left(1 + \frac{r}{100} \right)\times \left(1 + \frac{r}{100} \right)$$​​

Solution: 

Let the population two years ago is x 

So, 

​$$x \times \frac{102.5}{100} \times\frac{102.5}{100} = 84050$$ 

​$$x = 84050\times \frac{100}{102.5}\times\frac{100}{102.5} \\ \ \\ x = 80000$$​​

Thus, the population two years ago was 80000.