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(246) 4

Part of 1990 Tournament Of Towns

Problems(1)

TOT 246 1990 Spring O J4 counterfeit 2 of 61coins

Source:

3/12/2021
A set of 6161 coins that look alike is given. Two coins (whose weights are equal) are counterfeit. The other 5959 (genuine) coins also have the same weight, but a different weight from that of the counterfeit coins. However it is not known whether it is the genuine coins or the counterfeit coins which are heavier. How can this question be resolved by three weighings on the one balance? (It is not required to separate the counterfeit coins from the genuine ones.)
(D. Fomin, Leningrad)
combinatoricsweighings