Excel Solver | Why does Simplex LP not work on this model?

[MauWi]

Hi community,

first of all, I hope I post this under the right category and that there is someone who has experience with the excel solver function.

Attached, you can find:
(a) an assignment we have to do for a course in university
(b) my solution, which should theoretically work (also checked with the professor, who says the modelling is correct)
[I can't upload them here, but the files are available at my cross-post here]

The problem:
Despite the fact that everything seems to be modelled correctly, I can't run the solver with the linear SIMPLEX LP function, which is the only one that gives you the global optimum. However, others (whose models look pretty much the same) are able to use the SIMPLEX LP and the professor also said this is what she is aiming for.
I have been re-modelling it several times, but it doesn't work for some reason. Is anyone in here able to help?
Note: The mistake has to be somewhere in the demand constraint I believe.

Thanks so much in advance for your time - it is appreciated!
MauWi

 

[Peter_SSs]

Welcome to the MrExcel board!

In future, please make it clearer that you have cross-posted in another forum or forums as well as providing the link(s) to them. In this case I have done that for you with the addition of the blue text in your post. Also, make sure that you are familiar with #13 of the Forum Rules

Also note that providing files at other forums may not help much as helpers here may need to be members of that forum to access them. I suggest that you investigate XL2BB for providing sample data directly in your posts here.

 

[Hydraulics]

This is a problem of scaling, and it is a known "feature" as reported here.

Dividing inputs by 1000 is the easiest solution, another one is setting a higher tolerance for constraint precision, such as 0.001.

HTH,

Francesco