I think you are doing this really great project from the Science Buddies website:http://www.sciencebuddies.org/science-f ... #procedure
You have a very good question. Step 9b describes the dilution of your antifungal. The first step, adding 1/8 tsp antifungal to 9/8 tsp water is a 1:10 dilution. The next step, taking 1/8 tsp of the 1:10 dilution in 1/4 cup of warm water with sugar is a 1:100 dilution, so the final dilution is 1:1000 for the high concentration sample or 10 ug/mL
The procedure then suggests diluting the 1:1000 dilution by adding 1/8 tsp of the 1:1000 dilution to 1/14 cup of water with sugar. So the low concentration sample is 1:1000 x 1:100, or 1:100,000, or 0.1 ug/mL.
This is an example of of a dilution for a 1% antifungal. The procedure suggests checking the literature to find out what the effective concentration of the antifungal you will be working with. What antifungal agents are you testing?
If you followed this procedure and measured the amount of carbon dioxide produced, then your results are correct. When you do a science experiments until controlled conditions, your results are never incorrect.
However, if you obtained results that don't seem to make sense, please let us know what antifungal you used, what you did, and what your results were. Did you run a control with no antifungal? Did you repeat your results?
Please post again and explain why you are concerned about your results.