Answer :

Solution :

Let the Population of children = X

Then, Population of adult = 11000 – X

Population of children increasing by 11% and Population of adults is increasing by 20%

111%of children + 120% of adults = 12660

(X Å~ 111/100) + (11000 – X) Å~ 120/10 = 12660

By solving the above equation

X = 6000

Present Population of children = 6000

Present Population of adults = 5000

Rechecking-

6000 + 11% = 6000 + 660 = 6660

5000 + 20% = 6000

Total increased Population = 12,660