Three years before the population of a village was 10000. If at the end of each year, 20% of the people migrated to a nearby town, what is its present population?
To find: Present population of the village
Given: (i) Three years back population - 10000
(ii) Time – 3 years
(iii) Rate – 20% per annum
Number of people migrated on the very first year is 20% of 10000
$\Rightarrow \frac{10000 \times 20}{100}=2000$
People left after migration in the very first year = 10000 – 2000
= 8000
Number of people migrated in the second year is 20% of 8000
$\Rightarrow \frac{8000 \times 20}{100}=1600$
People left after migration in the second year = 8000 – 1600
= 6400
Number of people migrated in the third year is 20% of 6400
$\Rightarrow \frac{6400 \times 20}{100}=1280$
People left after migration in the third year = 6400 – 1280
= 5120
Ans) The present population is 5120