# Thread: Percentage Of Population Increase

1. ## Percentage Of Population Increase

In 1988 the population f Abra increased by 20% while the population of Cadabra decreased by 10% after which thw two populations were equal. What % of the original population of Cadabra was the orginal poplation of Abra?

2. Originally Posted by Rimas
In 1988 the population f Abra increased by 20% while the population of Cadabra decreased by 10% after which thw two populations were equal. What % of the original population of Cadabra was the orginal poplation of Abra?
population of Abra P.A. = x + 20%x = x(1+20%)
population of Cadabra P.C.= y(1- 10%)

then they becom equal so
x= y (1- 10%)/(1+20%)=9y/12

3. Originally Posted by Rimas
In 1988 the population f Abra increased by 20% while the population of Cadabra decreased by 10% after which thw two populations were equal. What % of the original population of Cadabra was the orginal poplation of Abra?
Hello,

let A be the population of Abra and
let C be the population of Cadabra.

Then you can set up the equation:

$\displaystyle 120\% A= 90\% C \Longrightarrow \frac{A}{C}=\frac{90\%}{120\%}=\frac{3}{4}$

That means the population of A was 3/4 = 75% of C.

EB