Question

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

Answer 1

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

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And if we somehow already know the true length to be `"12.2 m"` for some reason or another, then the percent error would be:

`barul|stackrel(" ")(" "%"error" = (|"measured" - "true value"|)/("true value") xx 100%" ")|`

And with your measured `"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 `"0.2 m"`, but the percent difference was `color(blue)(1.6%)`.