What you will want to provide is the Nth percentile of a model of the distribution of maximum wear of all three flutes. N is up to you.
You will be provided (next week) the scoring function, so you can use that to select N. There will be a small penalty for over-prediction (i.e., being too conservative), and a larger penalty for under-prediction (i.e., being too liberal), so you will have to make that tradeoff.