What does the symbol ± mean in scientific measurements?

[Kendo]

Not sure if this is the right "forum section" but what does "±" mean when it comes to writing a lab report? I don't remember this back in high school but idk.

 

[symbolipoint]

That symbol means, "plus or minus".
Also it can be read, "The positive or the negative of...".

 

[fresh_42]

$y= \pm \sqrt{x}$ means, that both possible values are considered, e.g. in $x_{1,2} = -\dfrac{p}{2} \pm \sqrt{\left( \dfrac{p}{2} \right)^2-q}\,.$ So it's $x_1=-\dfrac{p}{2} - \sqrt{\left( \dfrac{p}{2} \right)^2-q}$ and $x_2=-\dfrac{p}{2} + \sqrt{\left( \dfrac{p}{2} \right)^2-q}\,.$

$G = (6.674 08 \pm 0.000 31) \cdot 10^{-11} \,\dfrac{m^3}{kg \cdot s^2}$ means, that the gravitational constant isn't known exactly but only up to a certain amount of significant digits. It is around $6.674 08 \cdot 10^{-11} \,\dfrac{m^3}{kg \cdot s^2}$ but possible values range between $6.673 77 \cdot 10^{-11} \,\dfrac{m^3}{kg \cdot s^2}$ and $6.674 39 \cdot 10^{-11} \,\dfrac{m^3}{kg \cdot s^2}\,.$ Of course there is only one exact value, but we currently cannot measure it better than within this range.

 

[davenn]

but what does "±" mean when it comes to writing a lab report?

$y= \pm \sqrt{x}$ means, that both possible values are considered, e.g. in $x_{1,2} = -\dfrac{p}{2} \pm \sqrt{\left( \dfrac{p}{2} \right)^2-q}\,.$ So it's $x_1=-\dfrac{p}{2} - \sqrt{\left( \dfrac{p}{2} \right)^2-q}$ and $x_2=-\dfrac{p}{2} + \sqrt{\left( \dfrac{p}{2} \right)^2-q}\,.$

$G = (6.674 08 \pm 0.000 31) \cdot 10^{-11} \,\dfrac{m^3}{kg \cdot s^2}$ means, that the gravitational constant isn't known exactly but only up to a certain amount of significant digits. It is around $6.674 08 \cdot 10^{-11} \,\dfrac{m^3}{kg \cdot s^2}$ but possible values range between $6.673 77 \cdot 10^{-11} \,\dfrac{m^3}{kg \cdot s^2}$ and $6.674 39 \cdot 10^{-11} \,\dfrac{m^3}{kg \cdot s^2}\,.$ Of course there is only one exact value, but we currently cannot measure it better than within this range.

WOW could you make it any more difficult ??
it was a B level question

That symbol means, "plus or minus".
Also it can be read, "The positive or the negative of...".

Yes

so for example ...
I have a result of 50 ± 5 that is a result that is somewhere between 45 and 55 so the mid point is noted with the error margin
or I have a result of 100 ± 10% again the same thing but this time you are stating a percentage error margin

would be two easy examples of it's useDave

 

[FRANCOIS SIMON]

Not sure if this is the right "forum section" but what does "±" mean when it comes to writing a lab report? I don't remember this back in high school but idk.

The simplest way to define it: "±" indicates a tolerance of a given nominal value. For example, "The result of the poll is 60% against, with an error margin of ± 5%". So the result is between 65% and 55%.

 

[davenn]

The simplest way to define it: "±" indicates a tolerance of a given nominal value. For example, "The result of the poll is 60% against, with an error margin of ± 5%". So the result is between 65% and 55%.

did you read my post ?