i'm stuck trying to figure out how to do the statistical test for my biology experiment

Question

So I'm trying to see the effect of 2 different types of essential oils (rosemary and ginger) on e.coli. What I did was that I increased the concentrations of the oils and I used the disk diffusion tests and measured the inhibition zones formed. I also had a positive control being an antibiotic so I compare with that too. In addition to that I combined the two oils in 5 different ratios to see if there's a synergistic effect.

I also had 10 trials per concentration for each oil type. So that's 50 trials per type and 100 trials in total.

Question 1 (unrelated to question 2): So if I'm not wrong, I've got 2 independent variables and 1 dependent variable. Do the combination ratios count as a 3rd independent variable?

Question 2: I have watched a ton of YouTube videos on how to do the two-way ANOVA since I've got type and concentration. However, I am incredibly confused due to my very limited knowledge in statistics and do not have much time. I genuinely cannot understand how to carry it out. Also is Excel the right tool?

I don't know how to structure my table for the test either. Here are my results for the individual effect of varying concentrations of each essential oil: 

Answer 1

Hi Sara,

In regards to your first question:

1. Independent variables are factors that are manipulated. So your concentrations for example and the type of oil. The number of trials is not a factor that is manipulated.
2. You can use Excel for the two-way ANOVA test.

Feel free to schedule a session if needed to dive deeper into how to accomplish this.

Thank you,

Nick