Making a Mixture Design that Does Not Sum to 1.0

[#1]

I am trying to make an I-optimal mixture design with 3 components that add to 0.883, with the remainder 0.117 being a fourth, but constant, ingredient. I know a possible work around is to normalize my constraints, but to avoid confusion in reporting the information I would like to have the three components add to 0.883. I have tried to add linear constraints (shown in the attached screen shot) but I get an error. Please advise.

[#2 · Accepted solution]

There is a better way than using constraints.

From the red popup triangle by Custom Design choose Advanced Options > Mixture Sum and specify your sum of 0.883.

[#3]

Dan, thank you for the insight. I was wondering where that particular function was. This helps me tremendously.