You can your friend each have ten coins totally 49 cents. One of you loses one of the coins through a hole in your pocket. What is the chance it was a ten cent piece?

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The only way you can have 49 cents in ten coins is to have 4 1 cents coins, 3 fives and 3 tens. Regardless of which one of you lost the coin, you have a 3 in 10 chance of it being a ten cent piece. 

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