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# how to calculate propagation of errors?

I have a first year physics assignment, and I am completely lost.

Pfinal = 605 ± 5 Pa

Pinitial = 521 ± 5 Pa

the question is : ΔP = Pfinal -Pinitial

How do I do this!!? Any help would be greatly appreciated. Thank You :)

When I use an online propagation calculator, I get ΔP = 84 ± 7

### 1 Answer

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- 9 years agoFavorite Answer
It is very simple. ± 5 Pa Is the uncertaintey - error - of the value.

So, you subract the final value from the initial Pf-Pi

The error will be the sum of the relative errors, ie, 5/605 + 5/521, times 605+521, and you consign it as ± etc., AFTER you round it off to a single digit.

You can work it out from here on

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