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Double black (Posted on 2017-06-08) Difficulty: 3 of 5
Suppose there are three cards: a black card that is black on both sides,
a white card that is white on both sides, and a mixed card that is black on one side and white on the other.
All the cards are placed into a hat and one is pulled at random
and placed on a table.
The side facing up is black.

What are the odds that the other side is also black?

No Solution Yet Submitted by Ady TZIDON    
Rating: 2.6667 (3 votes)

Comments: ( Back to comment list | You must be logged in to post comments.)
re: D1? (spoiler) | Comment 2 of 4 |
(In reply to D1? (spoiler) by Steve Herman)

One could also argue that there only 2 cards with a black side, which is what we know from the chosen card. 

Only 1 of those 2 is black on both sides => probability of black-black is 1/2.
Which equates to odds of 1:1.

  Posted by JayDeeKay on 2017-06-08 11:21:59
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