Maths Olympiad Prep

Track / Stage 4 / 316 of 340 #576 of 1964

Problem 576

AMC 12 late, AIME early
Combinatorics Difficulty 5.0 Find the answer

2. In how many ways can the integers
5,4,3,2,1,1,2,3,4,5 -5,-4,-3,-2,-1,1,2,3,4,5
be arranged in a circle such that the product of each pair of adjacent integers is negative? (Assume that arrangements which can be obtained by rotation are considered the same.)

A number or a short expression. Fractions can be typed as 3/2, and spacing doesn't matter.

Official solution

2. 2880

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