1989 AIME Problems/Problem 11

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Problem

A sample of 121 integers is given, each between 1 and 1000 inclusive, with repetitions allowed. The sample has a unique mode (most frequent value). Let $D^{}_{}$ be the difference between the mode and the arithmetic mean of the sample. What is the largest possible value of $\lfloor D^{}_{}\rfloor$? (For real $x^{}_{}$, $\lfloor x^{}_{}\rfloor$ is the greatest integer less than or equal to $x^{}_{}$.)

Solution

This problem needs a solution. If you have a solution for it, please help us out by adding it. It is obvious that there will be n+1 values equal to one and n values each of 1000, 999, 998... . It is fairly easy to find the maximum. Try n=1 (yields 924) n=2 (yields 942) n=3 (yields 947) and n=4 (yields 944). The maximum difference occered at n=3, so the answer is 947.

See also