# CLASS-9POPULATION GROWTH WITH DIFFERENT PERCENTAGE & DIFFERENT TIME DURATION

POPULATION GROWTH WITH DIFFERENT PERCENTAGE & DIFFERENT TIME DURATION -

Let there be an increase in population at R₁% during 1st year and R₂% during 2nd year

R₁                  R₂

Then population after 2 years = P X ( 1 + ------ ) X ( 1 + ------ )

100                100

Example.1) Present population of a town is 1200000, if the population increase by 10% on 1st year, 15% in 2nd year, and in 3rd year increased by 10%, then calculate what will be the population after 3rd year.

Ans.) As we know from the above statement, 1st year increased by R₁ = 10%, 2nd year increased by R₂ = 15%, and 3rd year increased by R₃ = 10%. As we know the formulae –

Then population after 3 years =

R₁                   R₂                   R₃

P X ( 1 + ------- ) X ( 1 + ------- ) X ( 1 + ------- )

100                 100                  100

10                 15                 10

= 1200000 X ( 1 + ------ ) X ( 1 + ------ ) X ( 1 + ------ )

100                100                100

11           23            11

= 1200000 X ------- X -------- X --------

10           20            10

= 600 X 11 X 23 X 11 = 1669800

So, the population after 3 years would be 1669800     (Ans.)