Population of a small locality in $$1979 = 4000$$
Population of a small locality in $$1981 = 4500$$
So, increase in population $$= 4500 - 4000$$
$$= 500$$
Thus, percent increase in population
$$= \dfrac{500 }{ 4000} \times 100$$
$$= 50 / 4$$
We get,
$$= 12.5\%$$
Therefore, the population of the locality increased by $$12.5\%$$ in two years