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MathNet 2016-part-01 — 184 problems (EN–VI) Question 157

Math Olympiad Vault · MathNet 2016-part-01 — 184 problems (EN–VI)

Question 157

The integers $1$, $2$, $3$, $\ldots$, $2016$ are written on a board. You can choose any two numbers on the board and replace them with their average. For example, you can replace $1$ and $2$ with $1.5$, or you can replace $1$ and $3$ with a second copy of $2$. After $2015$ replacements of this kind, the board will have only one number left on it.

a. Prove that there is a sequence of replacements that will make the final number equal to $2$.

b. Prove that there is a sequence of replacements that will make the final number equal to $1000$.