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MathNet 2011 Question 66

Math Olympiad Vault · MathNet 2011

Question 66

Let $n$ be a positive integer and let $x_1, x_2, \dots, x_n$ and $y_1, y_2, \dots, y_n$ be real numbers. Prove that there exists a number $i$, $i = 1, 2, \dots, n$, such that
$$
\sum_{j=1}^{n} |x_i - x_j| \le \sum_{j=1}^{n} |x_i - y_j|.
$$