Quote from igsi:
Now I see what was my mistake. I was not taking into account that the card itself and what side is up are both choosen randomly. So, my reasoning would be correct if the problem was stated differently.
"Three cards are placed into a hat. One card has a white face on both sides. A second card has a white side and a red side and the third card has two red sides.
A card is drawn out of the hat and we are told that one side of that cards is red. What is the probability that that card is the card with two red sides?"
The answer to this problem is 50%. Bottom line, the history is important!
I still agree. This was your original answer and my original resonse was posted as below. I believe it ALL is exactly as you explained, and I agreed. It is about the probabilities AFTER an action has occured, which changes the entire "problem".
Quote from rs7:
Makes sense to me! Especially since the problem was stated as it was. If the problem was worded differently, such as PRIOR to any event, then yes, I could see how the 66% answer would make sense. But the wording seemed to clearly indicate that one event had already occurred. Which would change the probability (as far as I can understand this).
On the other hand, it is never wise to be on the wrong side of an assessment by MrSub. He is rarely if ever wrong. So that has to be taken into serious consideration.
Peace,
