Standard Deviation of a calculated variable

Dave P · science forum beginner Joined: 23 Jun 2006 Posts: 3

I have collected data of two measured variables A and B. The client wants to know the standard deviation of A/B.
For example,
A B A/B
--- --- ---
24 3 8
4 1 4
--- --- ---
28 4 7 not 6 (Mean is 7 not 6)

The mean of A/B must be calculated from the sums of A and B but how do I determine the standard deviation of A/B? A further complication is that each sample is weighted as well. For example, the first sample might weigh 10kg and the second sample might weigh 3 kg.

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