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Taiwan APMO Prelininary
2021 Taiwan APMO Preliminary First Round
3
3
Part of
2021 Taiwan APMO Preliminary First Round
Problems
(1)
Skull,coin possibility
Source: 2021 Taiwan APMO Preliminary First Round
11/21/2020
Let a board game has
10
10
10
cards:
3
3
3
skull cards,
5
5
5
coin cards and
2
2
2
blank cards. We put these
10
10
10
cards downward and shuffle them and take cards one by one from the top. Once
3
3
3
skull cards or coin cards appears we stop. What is the possibility of it stops because there appears
3
3
3
skull cards?
combinatorics
possibility