There are four balls in a hat: a blue one, a white one, and two red ones. Now I draw simultaneously two balls, look at them, and announce that at least one of them is red.
What is the chance that the other is red as well?
I believe that both sides want to justify their original answers.
Still, reading the text carefully, only .20 qualifies (!).
There was no previous protocol referring the format of
my announcement , no other color was mentioned and on top of that
the initial content of 3 colors precludes a question "if there is at least one white marble, what is the chance that the other is white as well?"
- such a question would trigger a quip "No way", not a "1/3".
In retrospect, the only fault in my puzzle was grading it d2.