Maths Olympiad Prep

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, 2010

Number theory Difficulty 2.0 Junior Prove it Canada

(a) Determine the average of the integers 71,72,73,74,7571, 72, 73, 74, 75. (b) Suppose that n,n+1,n+2,n+3,n+4n, n+1, n+2, n+3, n+4 are five consecutive integers. (i) Determine a simplified expression for the sum of these five consecutive integers. (ii) If the average of these five consecutive integers is an odd integer, explain why nn must be an odd integer. (c) Six consecutive integers can be represented by n,n+1,n+2,n+3,n+4,n+5n, n+1, n+2, n+3, n+4, n+5, where nn is an integer. Explain why the average of six consecutive integers is never an integer.

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Source: CEMC, University of Waterloo, licensed CC-BY-NC-4.0. Statement reproduced verbatim; metadata (topic, difficulty) added by this project. Solutions are the publisher's, linked not copied.