Difference between revisions of "2023 AMC 12A Problems/Problem 21"

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==Problem==
 
==Problem==
If <math>A</math> and <math>B</math> are vertices of a polyhedron, define the <math>distance d(A,B)</math>
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If <math>A</math> and <math>B</math> are vertices of a polyhedron, define the distance <math>d(A,B)</math>
 
C to be the minimum number of edges of the polyhedron one must traverse in order to connect <math>A</math> and <math>B</math>. For example, if AB is an edge of the polyhedron, then <math>d(A, B)</math> = 1, but if AC and CB are edges and AB is not an edge, then <math>d(A, B)</math> = 2. Let Q, R, and S be randomly chosen distinct vertices of a regular icosahedron (regular polyhedron made up of 20 equilateral triangles). What is the probability that <math>d(Q, R) > d(R, S)</math>?
 
C to be the minimum number of edges of the polyhedron one must traverse in order to connect <math>A</math> and <math>B</math>. For example, if AB is an edge of the polyhedron, then <math>d(A, B)</math> = 1, but if AC and CB are edges and AB is not an edge, then <math>d(A, B)</math> = 2. Let Q, R, and S be randomly chosen distinct vertices of a regular icosahedron (regular polyhedron made up of 20 equilateral triangles). What is the probability that <math>d(Q, R) > d(R, S)</math>?
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==Solution 1==
 
==Solution 1==
  

Revision as of 21:53, 9 November 2023

Problem

If $A$ and $B$ are vertices of a polyhedron, define the distance $d(A,B)$ C to be the minimum number of edges of the polyhedron one must traverse in order to connect $A$ and $B$. For example, if AB is an edge of the polyhedron, then $d(A, B)$ = 1, but if AC and CB are edges and AB is not an edge, then $d(A, B)$ = 2. Let Q, R, and S be randomly chosen distinct vertices of a regular icosahedron (regular polyhedron made up of 20 equilateral triangles). What is the probability that $d(Q, R) > d(R, S)$?

Solution 1

See also

2023 AMC 12A (ProblemsAnswer KeyResources)
Preceded by
First Problem
Followed by
Problem 22
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
All AMC 12 Problems and Solutions

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