Any Maths experts around?

[Julian Bond <julian_bond@voidstar.com>]

Off topic, although I need it for a syndication design involving
ratings.

Does anyone know the stats algorithm for generating a new standard
deviation for a population field combined from two smaller fields where
the population size, mean and std are known for the two fields?

eg Sample results one has M1, F1, S1, Sample two has M2, F2, S2. Now
M3=(M1*F1+M2*F2)/(F1+F2) but what would S3 be? 

If you don't have a solution, do you know a URL that does?  

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Julian Bond    email: julian_bond@voidstar.com
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