mathcounts notes

Problem. Dennis rolls three fair six-sided dice, obtaining a, b, c ∈ {1,…,6}. Find \[ \mathbb{E}\!\bigl[\,|a-b|+|b-c|+|c-a|\,\bigr]. \] ...

Questions written by Willie, a volunteer.  Answer key and detailed solutions below. 1a. There is a regular cylinder, which has a height ...

There are numerous similar triangle questions on Mathcounts. Here are the basics: If two triangles are similar, their correspond...

For Mathcounts advanced group -- harder  Mathcounts State/National problem on 3-D geometry.                       From Mathcounts Mini : ...