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Open By Majority (Posted on 2004-03-03) Difficulty: 3 of 5
A group of five people want to put a set of locks on a chest and distribute keys to the locks amongst themselves in such a way that all the locks on the chest could be opened only when at least three of them were present to open it.

How many locks would be needed, and how many keys?

See The Solution Submitted by Brian Smith    
Rating: 4.1429 (7 votes)

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Possible Solution | Comment 19 of 45 |

Hi all

I have a possible solution to the problem:

if you have a combination of 5 people of which any 3 have to be able to open all the locks then you have to have a C(5,3)=10 unique locks and 3 cheys per lock = 30 keys divided by 5 people = > 6 keys/ person

 


  Posted by Stelian Trandafir on 2004-03-04 07:28:29
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