While some questions may be logical, some come across the wrong way. The wording makes it sound like your a weaker candidate that fears not making it through training and if you do, you are not sure you could make it though an upgrade.
This may not be true at all, but the person interviewing a person asking some of these questions will not be viewed as a possible new hire.
It should not matter how many did or did not make it through training, as others have nothing to do with you or your ability.
Ron