Maths Olympiad Prep

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Algebra Difficulty 4.9 AIME Find the answer

1.1. Five non-negative numbers are written in a row. The sum of any two adjacent numbers does not exceed 1. What is the maximum value that the sum of all five numbers can take?

A number or a short expression. Spacing and $ signs are ignored.

Solution

1.1. Answer: 3. Example: 1,0,1,0,11,0,1,0,1.

Denoting our numbers as a,b,c,d,ea, b, c, d, e, we get that a+b+c+d+e=(a+b)+(c+d)+(d+e)d3a+b+c+d+e=(a+b)+(c+d)+(d+e)-d \leqslant 3.

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Source: NuminaMath-1.5, licensed Apache-2.0. Statement and solution reproduced as published; topic and difficulty added by this site.