Mixed apparent attenuation calculation

[chris2012]

Hi,

I'm wondering if anyone could point me in the right direction.

I know if I just have say 10kg sucrose in 20l of water, I can get an OG of 1.19195.

And calculate FG with an apparent attenuation of 122%:

1.19195-(((1.19195-1)*(122/100))) = 0.957771 FG

Also if I have a wort created from 1kg pale, with a 20l batch size, with a yeast with an apparent attenuation of 72%:

og = 1.01497
fg = 1.01497-(.01497*(72/100)) = 1.0041916

What I'm struggling to find information for, is how to calculate the FG for a mixture of wort + sucrose:

So for instance if I have wort from malt 1kg pale + 10kg table sugar in a 20l batch:

I notice you can seemingly add the SGs from each addition together, to get the OG:

malt 1kg pale:
og = 1.01497

sugar:
og = 1.19195

malt 1kg pale: + sugar:
simply adding the two sgs ((1.01497-1) + (1.19195-1))+1 = 1.20692 seems to give the OG

But what I'm struggling to work out, is how to calculating the FG for a solution of wort with sucrose, assuming 122% apparent attenuation for the sucrose and 72% attenuation for the wort part.

Any pointers to standard calculations would be most appreciated!

cheers
Chris

 

[chris2012]

I think I worked it out, you can seemingly sum the two separate FGs for sugar + malt doing:

(FG1 + FG2) - 1