Thank you for your question, and welcome to science buddies.
You didn't mention on what system/program you were going to build your model of predator and prey. However, what if you modeled a population of each, using numbers from the real world, like the average heard (H_ave) size of say wildebeest and an average pride of lions (P_ave). Using statistics, you could model the predators probability of kill (pK) vs the preys probability of survival (pS) and determine ranges of population size , kill/survival rates that promote a balanced eco-system (of course neglecting many other environmental factors).
You would need to build this model in a constructive computer model and using a "monte-carlo" simulation technique change your variables, pK, pS, H_ave, and P_ave.
Just a thought. Post back if you have any other questions or need more ideas.
Hope this helps.
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