What is the Correct Way to Calculate Relative Improvement and Percentage?

[Niles]

Homework Statement

Hi guys

Say I go from 10 to 8. Is the relative improvement given by

(1-10/8) = 0.25,

i.e. 25%?


Niles.

 

[zgozvrm]

First of all, you forgot the sign. The result of your formula should have been -25%, which makes sense because the 2nd value is less than the first.

Secondly, that is not correct. Think about it this way: to decrease some number by 25% means to take 1/4 of the original number away.
In other words X - (0.25)X which is equal to 0.75X.

In your case, decreasing 10 by 25% gives you (0.75) * 10 = 7.5