Given: Increase in population for 2 years = 25% No. of villagers who left in third year = 500 Decrease in population in fourth year = 10% Population at the end of fourth year = 6750 Concept used: Indirect method: If 10% increment in number and number becomes a , then original number =a×(100/110). Calculation: At the beginning of fourth year, ⇒6750×(100/90)=7500 At the beginning of third year, ⇒7500+500=8000 At the beginning of first year, ⇒8000×(100/125)×(100/125) ⇒5120 ∴ The population of the village at the beginning of the first year is 5120.