"Impossible" means "impossible", not "unbelievably improbable".
That's even more true when you ask about "mathematically impossible", as it reinforces the idea of formal logic being the relevant domain, where precise meaning of words is fundamental.
If you adjust your question to be "at what probability is it unreasonable to claim these problems are unrelated?", then the answer is subjective - different people have different standards for reasonability.
I think we'd need mountains more data than we have about the incidents to compute a meaningful probability, anyway.
"Impossible" means "impossible", not "unbelievably improbable".
That's even more true when you ask about "mathematically impossible", as it reinforces the idea of formal logic being the relevant domain, where precise meaning of words is fundamental.
If you adjust your question to be "at what probability is it unreasonable to claim these problems are unrelated?", then the answer is subjective - different people have different standards for reasonability.
I think we'd need mountains more data than we have about the incidents to compute a meaningful probability, anyway.