IMO Shortlist 1979 problem 2


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2. travnja 2012.
1979 shortlist
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From a bag containing 5 pairs of socks, each pair a different color, a random sample of 4 single socks is drawn. Any complete pairs in the sample are discarded and replaced by a new pair draw from the bag. The process continues until the bag is empty or there are 4 socks of different colors held outside the bag. What is the probability of the latter alternative?
Izvor: Međunarodna matematička olimpijada, shortlist 1979