Room 325 ILB, by the deadline stated on the contest flyer available at the department office. Each solution must be detailed and complete. Guessing or methods of crude approximation are not acceptable. The winning entries will be picked by the Problem Contest committee. Their decisions will be final.
Someone erases exactly one of the numbers.
The average of the remaining numbers is 111 and 10 seventeenths. Find n and the number that was erased. Here's a solution in pdf format. The Pythagorean Theorem Revisited Consider the tetrahedron in 3-dimensional space pictured below. Prove that the following relationship holds between the areas of the four triangles that form the sides of the tetrahedron.