I created six hundred coins. I tell you that each is red on one side, but may be red or blue on the other side. I flip each coin, and show you the resulting colors. You count 400 red and 200 blue. What is your best estimate of the number of coins that are red on both sides?

I flipped all the same coins again, and you count 350 red and 250 blue. How should you modify your estimate?

If I know that the coins are guaranteed to have at least one red side, then telling me that 200 blue sides showed up, would mean that 400 of the coins must have been red/blue. 

If 400 of the coins were red/blue, and there are 600 coins total, then 200 of the coins must have been red/red.

Posted by John zadeh on 2007-06-25 22:29:04