TOT 2000 Autumn OJ4 32 coins , 30 real and 2 fake
Source:
May 10, 2020
weighingscombinatorics
Problem Statement
Among a set of coins , all identical in appearance, are real and are fake. Any two real coins have the same weight . The fake coins have the same weight , which is different from the weight of a real coin. How can one divide the coins into two groups of equal total weight by using a balance at most times?(A Shapovalov)