I have a bag which contains three coins. One of them is red on one side, blue on the other; another of them is red on one side and green on the other; and the third is blue on one side and green on the other.

I would like to lay them out on the table so that one of each color is facing up.

I reach into the bag and randomly select a coin. I flip it onto the table and it lands red side up (you cannot see what color is on the other side).

Not wanting to risk flipping another red side up, I reach into the bag and look for a coin with a green side, and place it green side up on the table (once again you have no idea what color is on the other side).

If I were to take the last coin out of the bag and flip it, what is the probability that it will land with a blue side facing up?

6 sides. Each color has 2 chances. 1 red showing, 1 green showing. That leaves 1 more red, 1 more green, and two more blues. So, 2 out of 4 chances are blue.

Posted by Gina Ernyey on 2006-05-25 18:06:52