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Counting & ProbabilityChallengeExpected Value, Linearity & Advanced Probability

Expected Value, Linearity & Advanced Probability · Challenge problem

A permutation π\pi of {1,2,…,10}\{1,2,\dots,10\} is chosen uniformly at random. Find the expected value of ∑i=110∣π(i)−i∣\displaystyle\sum_{i=1}^{10}\left|\pi(i)-i\right|, the total displacement of the permutation.