It can be 0... That's a fact.
I just gave two recent examples. How can it have zero probability?
Sorry, it was a typo, I want to say "can't".
I have seen both scenarios in the past, the one that shows us 1 block in 1 hour, and the one that shows us 5 blocks in 10 minutes... And the first scenario feels terrible, waiting more than 1 hour for a confirmation is a nightmare.
Getting back to the main question, what's the probability? i would say 33%, because having 1 block in 10 minutes has a chance of 100%, having 2 is 50%, and 3 33%... But my logic is too basic, as i mentioned in the past post, a lot of facts are involved.