MathDB

1

Part of 1987 Poland - Second Round

Problems(1)

numbered balls

Source: Polish MO Recond Round 1987 p1

9/9/2024
From an urn containing one ball marked with the number 1, two balls marked with the number 2, ..., n n balls marked with the number n n we draw two balls without replacement. We assume that each ball is equally likely to be drawn from the urn. Calculate the probability that both balls drawn have the same number.
combinatorics