Remaining population after percentage change = Initial population × (1 - Percentage change ). To find the ratio of initial population to present population: Ratio = Initial population ∕ Current population . Calculation: Remaining population after 15% left =P×(1−15∕100) Remaining population =P×85∕100 Remaining population after 60\% of above left =(P×85∕100)×(1−60∕100) Remaining population =(P×85∕100)×40∕100 Current population =(P×85×40)∕10000 3400=(P×85×40)∕10000 ⇒P=(3400×10000)∕(85×40) ⇒P=34000000∕3400 ⇒P=10000 Initial population =10000. Ratio = Initial population ∕ Current population Ratio =10000∕3400 ⇒ Ratio =100:34 ⇒ Ratio =50:17