Question

The population of a city increases each year by 4% of what it had been at the beginning of each year. If the population in 1999 had been 6760000, find the population of the city in (1) 2001 (ii) 1997.

Answer 1

Given details are,

Annual increase rate of population of city is = 4%

Population in 1999 was = 6760000

(i) Population of the city in 2001 (2 years after)

By using the formula,

A = P (1 + R/100)

x = 6760000 (1 + 4/100) (1 + 4/100)

= 6760000 (104/100) (104/100)

= 6760000 (1.04) (1.04)

= 7311616

∴ Population in the year 2001 is 7311616

(ii) Population of city in 1997 (2 years ago)

By using the formula,

A = P (1 + R/100)

x = 6760000 (1 – 4/100) (1 – 4/100)

= 6760000 (96/100) (96/100)

= 6760000 (0.96) (0.96)

= 6230016

∴ Population in the year 1997 was 6230016.