IMC 2015 Q7
7. A tetrahedron is a solid figure which has four faces, all of which are triangles.
What is the product of the number of edges and the number of vertices of the tetrahedron?
- A 8
- B 10
- C 12
- D 18
- E 24
Intermediate Mathematical Challenge 2015, Question 7. © UK Mathematics Trust. Original paper on ukmt.org.uk
Answer: E 24
The tetrahedron has 6 edges and 4 vertices, so the required product is 6 × 4 = 24.
Solution © UK Mathematics Trust, from the IMC 2015 solutions. Longer versions with investigations: Solutions and investigations (PDF).