## Re: AI-GEOSTATS: Calculating averages

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• Calculating averagesCraig, Don t you mean multiply Average Nickel Head grade by Average Mill recovery. Your first figure 0.3342 is correct but your figure
Message 1 of 3 , Jan 5, 2003
Calculating averagesCraig,
is incorrect. It is your assumption that your average mill recovery is
tonneage recovery, i.e. you averaged the mill recovery as if it where
recovery per tonne of ore instead of per % of metal so your calculation
of 0.5557*0.56857 is incorrect.

Your average mill recovery should be calculated

(0.53*60)+(0.65*62)+(0.32*20)+(0.8*70)+(0.56*63)+(0.45*55)+(0.58*0.68)/
(0.53+0.65+0.32+0.8+0.56+0.45+0.58) =0.601465

So your original table should look like;

Nickel Mill Recovered
0.53 60 0.3180
0.65 62 0.4030
0.32 20 0.0640
0.8 70 0.5600
0.56 63 0.3528
0.45 55 0.2475
0.58 68 0.3944
Average 0.555714286 60.14652956 0.3342

divided by Average Mill Recovery ====> 0.334242857

Regards Digby Millikan
Geolite Mining Systems
digbym@...
http://www.users.on.net/digbym

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• Hi Craig The average of a product will only equal the product of the averages if the two numbers are completely independent of one another. This is exactly
Message 2 of 3 , Jan 5, 2003
Hi Craig

The average of a product will only equal the product
of the averages if the two numbers are completely
independent of one another.

This is exactly analogous to the calculation of a
covariance in statistics.

Isobel
http://uk.geocities.com/drisobelclark

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