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Six hundred coins (Posted on 2006-12-22) Difficulty: 2 of 5
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?

See The Solution Submitted by Tristan    
Rating: 4.5000 (2 votes)

Comments: ( Back to comment list | You must be logged in to post comments.)
Some Thoughts re: I might think you cheated. | Comment 4 of 12 |
(In reply to I might think you cheated. by Jer)

"The probability of 200 or fewer blue occurring when these are all flipped is (using the notation of a TI-83 calculator) binomcdf(n,.5,200)"

But you don't want this -- you want the probability of getting EXACTLY 200 blues.

  Posted by Federico Kereki on 2006-12-22 14:13:46

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