How many coins need to be released so that chances are that one coin will make it all the way down the slide?
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Friday, November 12, 2010
Sliding Coins
How many coins need to be released so that chances are that one coin will make it all the way down the slide?
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Chances for a coin to get past the first hole are 1:2, chances to pass the second hole are then 1:2 x 1:2 = 1:4, and finally chances to pass the third hole are 1:4 x 1:2 = 1:8.
ReplyDeleteWe should release 8 coins and theoretically one of them should make it all the way down.
Why do I get a feeling it can't be that simple?
Hmmm.... I think it depends how you interpret "...the chances are...".
ReplyDeleteFor example, with seven roles there is a 39% chance (i.e (7/8)^7) that no coins would make and, therefore, a 61% (1-0.39) that at least one coin would make it. So the chances are that at least one coin would make it.
Similarly, for 6 coins there is a 45% that no coins will make it and a 55% chance that at least one will. So, agian, the chances are that at least one coin would make it.
1 coin
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