# percentage increases

• Sep 17th 2011, 09:07 AM
Lumos1997
percentage increases
helloo :)
so i got this question for homework, and its the following:

$125is increased by 25%. by what percentage, correct to 3 significant figures, must$80 be increased to give the same result?

all that i have so far is that the $125 increases to 152.25. and now im stuck • Sep 17th 2011, 09:38 AM e^(i*pi) Re: percentage increases Quote: Originally Posted by Lumos1997 helloo :) so i got this question for homework, and its the following:$125is increased by 25%. by what percentage, correct to 3 significant figures, must $80 be increased to give the same result? all that i have so far is that the$125 increases to 152.25. and now im stuck

125 increases to 156.25: $\displaystyle 125(1+1.25) = 156.25$

An unknown percentage increase from $80 is$\displaystyle 80\left(1+\dfrac{x}{100}\right)$and since you know it must be equal to 156.25 set them equal and solve for x (which will be in percentage terms):$\displaystyle 80+\dfrac{4x}{5} = 156.25\$