3 faced of regular tetrahedron are painted in white and one in black
Source: 1997 German Federal - Bundeswettbewerb Mathematik - BWM - Round 2 p1
January 27, 2020
Coloringtetrahedroncombinatorics
Problem Statement
Three faces of a regular tetrahedron are painted in white and the remaining one in black. Initially, the tetrahedron is positioned on a plane with the black face down. It is then tilted several times over its edges. After a while it returns to its original position. Can it now have a white face down?