9. The Socks
Cathy has twelve black socks and twelve white socks in her drawer.
In complete darkness, and without looking, how many socks must she take from the drawer in order to be sure to get a pair that match?
Added 1 January 2007
Solution:
3
Socks do not come in in left and right, so any black will pair with any other black and any white will pair with any other white. If you have three socks and they are either colored black or white, then you will have at least two socks of the same color, giving you one matching pair.
Comments (10)
The answer to number 10 is incorrect. If the socks are in pairs, then she only needs to grab 2 socks as they are already paired.
The answer to the sock puzzle is incorrect. If the socks are already paired, she only needs to grab 2 socks to ensure she has a matching pair.
Many socks, including the drifit ones from Nike, are specific to either your right or left foot. Hence solving the problem is no longer logic but rather statistics, since most people still wear dual wield socks.
In my opinion, the answer to the socks problem is wrong. You need to pick 13 socks in the blind to make sure that you have at least one matching pair. Your first twelve picks could be the same color.
To be sure you have a matching pair, you need to take at least 13 socks because you may take the first 12 socks of the same color.
The puzzle about the fingers on the left hand is misleading. The statement that thumbs are considered fingers creates confusion about the assumptions regarding the number of fingers.
For the socks problem, why did you not specify in the first place there are no left and right socks? It is said in the answer but why would you bother explaining something if it wasn't unclear in the first place? Because it's unclear.
The title 'The Socks' seems misleading for an easy puzzle. Could you clarify the reasoning behind this naming?
This is wrong! You could pull out 3 of the same color.
Your answer of 3 is contestable. You reason that since socks have no right or left, any 3 socks allows you to gather a matching pair. If we are to assume that all 12 white and 12 blacks are mixed in the same drawer, randomly picking 3 socks of the 24 can lead to 3 whites or 3 blacks.
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