I have a rather easy question: I have a batch of different dried fruits, let's say n=100, with a diameter of 8±2 cm, 2 being the standard deviation. After throwing them in water the distribution of the batch's diameters is let's say 16±5 cm because of the swelling. This results in a size ratio of 2, but what about the standard deviation of this calculation?

I tried propagation of uncertainty with covariance=0, so:

**σ**(A/B) ≈A/B*SQRT( (a/A)^2 +(b/B)^2 ). a and b are the standard deviation of A and B, respectively.

Hi,

I have a rather easy question: I have a batch of different dried fruits, let's say n=100, with a diameter of 8±2 cm, 2 being the standard deviation. After throwing them in water the distribution of the batch's diameters is let's say 16±5 cm because of the swelling. This results in a size ratio of 2, but what about the standard deviation of this calculation?

I tried propagation of uncertainty with covariance=0, so:

**σ**(A/B) ≈A/B*SQRT( (a/A)^2 +(b/B)^2 ). a and b are the standard deviation of A and B, respectively.

When using my example I get 0.8, so is the size ratio of the two population 2±0.8? This seems not too bad given that the extreme ratios 21/6 and 11/10 are 3.5 and 1.1, respectively.

Thanks a lot for the feedback, curious to see whether this is good enough or if there are better means.