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## 'A Mean Tetrahedron' printed from http://nrich.maths.org/

A tetrahedron has 4 vertices, 6 edges and 4 faces. Can you
number them 1 to 14 in such a way that the number on each edge is
the mean of the two numbers at the vertices joined by that edge and
also the mean of the two numbers on the faces it separates?