Fractional uncertainty and propagation of uncertainties

[quietrain]

erm, ok let's say i have a value, with uncertainty, like y = 10 ± 3

so let's say i multiply y by 2, then it becomes 20

but does the uncertainty becomes 3 x 2 = 6? , hence y = 20±6 ?

what about divide? does it becomes 1.5?

i roughly understand fractional uncertainty and propagation of uncertainties, but what if i multiply the value of y with a constant as in the case above. what will become of the uncertainty?

thanks for help!

 

[Vanadium 50]

Yes, in that case the uncertainty scales.

Think about it this way - if you know the radius of a circle is 10 ± 3, you don't know the diameter any better than ± 6, right?

 

[quietrain]

ah i see thanks a lot!