# You measure a piece of rope and find its length to be 12 m. How do you find the percent error of this measurement?

Aug 27, 2017

You can only do so by knowing its actual length, which you have not provided.

And if we somehow already know the true length to be $\text{12.2 m}$ for some reason or another, then the percent error would be:

$\overline{\underline{|}} \stackrel{\text{ ")(" "%"error" = (|"measured" - "true value"|)/("true value") xx 100%" }}{|}$

And with your measured $\text{12 m}$, then it would be:

= (|12 - 12.2|)/(12.2) xx 100%

= 1.64%

Given the measurement was made to two significant figures, the difference was $\text{0.2 m}$, but the percent difference was color(blue)(1.6%).