The population of a town increases by 25% during 1991. By what percent must it decrease the following year to return to the population it was at the beginning of 1991?

Question

I thought the answer was 25% but i don't know for sure.

Answer 1

that's what happens when you guess instead of calculate. You are decreasing a larger number, so the % is less:

1.25 * r = 1
r = 1/1.25 = 0.80 = 80%

So, you just have to give a 20% discount to get back to the original price.

Answer 2

What percent of 20 is 13?

I got the answer as 65% but I am not sure.

Answer 3

What percent of 20 is 13?

Answer 4

Find the GCD of 36, 27, and 45.

Answer 5

Considering a population "x" at the beginning of 1991 and "y" at the end, we have:
y = x.(1+1/4) = x.5/4
So now we have to decrease the population y by i% to get x:
x = y.(1-i) <=> x = x.5/4 - x.5/4.i <=> 1 - 5/4 = -5/4.i <=> i = 1/5
So y has to be decreased by 20%.