Given,
Annul increase rate of population of town = 40/1000× 100 = 4%
Present population of town = 175760
So, let the population of town 3 years ago be = x
By using the formula,
A = P (1 + R/100)
175760 = x (1 + 4/100) (1 + 4/100) (1 + 4/100)
175760 = x (104/100) (104/100) (104/100)
175760 = x (1.04) (1.04) (1.04)
175760 = 1.124864x
x = 175760/1.124864
= 156250
∴ Population 3 years ago was 156250.