Olympiad Maths Prep

Track / Stage 4 / 44 of 340 #304 of 2000

Problem 304

AMC 12 late, AIME early
Combinatorics Difficulty 4.7 Find the answer

4. Fill the numbers 1,2,3,4,5,61, 2, 3, 4, 5, 6 into the 6 vertices of the hexagon ABCDEFA B C D E F, and let S1,S2,,S6S_{1}, S_{2}, \cdots, S_{6} represent the sums of the numbers at the 3 adjacent vertices (A,B,C),(B,C,D),,(F,A,B)(A, B, C), (B, C, D), \cdots, (F, A, B) respectively.
(1) Try to give a way to fill the numbers so that S1,S2,,S6S_{1}, S_{2}, \cdots, S_{6} are all greater than or equal to 9;
(2) Can you find a way to fill the numbers so that S1,S2,,S6S_{1}, S_{2}, \cdots, S_{6} are all greater than or equal to 10? If yes, provide a specific way to fill the numbers; if not, explain the reason.

Official solution

4. (1) There are many ways to fill, omitted. (2) They can all be greater than or equal to 10, see Figure 7.

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