Printable

2020 AMC 10B Problem 17

Include the solution Back to the problem

2020 AMC 10B Problem 17AMC 10 Step by Step

Name: Date: September 13, 2026

Basic Counting · difficulty 4 of 5 · about 7 min · position P16-20

There are $10$ people standing equally spaced around a circle. Each person knows exactly $3$ of the other $9$ people: the $2$ people standing next to him or her, as well as the person directly across the circle. How many ways are there for the $10$ people to split up into $5$ pairs so that the members of each pair know each other?

A)
$11$
B)
$12$
C)
$13$
D)
$14$
E)
$15$

2020 AMC 10B Problem 17

Working