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Four balls (Posted on 2017-05-19) Difficulty: 2 of 5
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?

See The Solution Submitted by Ady TZIDON    
Rating: 3.5000 (2 votes)

Comments: ( Back to comment list | You must be logged in to post comments.)
Solution re(2): Who's right | Comment 12 of 22 |
(In reply to re: Who's right by hoodat)

Maybe another way of saying it will help. 

If 6 people did this, 4 would have one red and one nonred, 1 would have two nonred and 1 two red. Of those that have one of each, 2 would say they have at least one red and 2 would say at least one specific other color. The 1 with two reds of course will day at least one red. 

So out of the 3 saying at least one red, only 1 has both red.

  Posted by Charlie on 2017-05-21 16:37:54
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