Present population of a city is 90 lac. What will be the population of the city after 3 years if the growth rate of population of that city is 40 per thousand?

Question: Present population of a city is 90 lac. What will be the population of the city after 3 years if the growth rate of population of that city is 40 per thousand?

Solution:
Given,
Present population of the city is P = 90,00,000
growth rate of population, r = (40/1000) × 100%
= 4%
time n = 3 years

Here, in the case of growth of population, formula for compound principal is applicable
∴ C = P(1 + r)ⁿ
= 90,00,000(1 + 4/100)³
= 90,00,000(104/100)³
= 90,00,000 × (104/100) × (104/100) × (104/100)
= 9 x 104 x 104 x 104
= 1,01,23,776