Una ciudad tenía 8000 habitantes a final del año 2000. Cada año su población se incrementa en un 0.5 %

¿Al final de qué año está ciudad tendrá más de 81,200 habitantes?

The correct answer is 2030.

Step-by-step explanation:

To start we must analyze the information we have.

We know that a city has 8000 inhabitants and that each year this number increases by 0.5%. That means that each year it has 40 more inhabitants:

(8000 . 0,5) : 100 = 40

Having this information we could do a cross multiplication:

1 year 40 inhabitants

x years 81200

81200 = 40.x

x = 81200 : 40

x = 2030

In this way we can verify that the correct answer is 2030.