If you assume the problem is correct, in other words one and only one of the four answers is correct, then you have to exclude the two identical answers (25%). You are left with 50% and 60%. You pick one of them at random, and the chance to be correct is 50%.
If you start with the assumption that the problem is wrong, then ... it's wrong.
I see that despite getting 3 upvotes in a matter of minutes, this item is now ranked down in the mid 400s. Clearly it's been flagged.
Would someone please explain why this is sufficiently inappropriate to deserve getting flagged? I just want to know so I can avoid submitting the wrong kind of items.
I'm not sure. I think it's a thorough analysis of this so-called "problem" that made the rounds. I especially appreciated the conclusion, that not only is it not a paradox with no answer, but a broken paradox at that.
If you start with the assumption that the problem is wrong, then ... it's wrong.