## ________________

The coach loves to pose problems involving weight to refine the team’s logical and analytical skills.

## ________________

### Nine Coins

The coach provides the team with nine coins that are identical in appearance, telling them that three of the coins weigh 3 units each, three weigh 2 units each, and three weigh 1 unit each. Hannah knows what each coin weighs, but needs to convince the coach that she knows.

How many weighings on a simple two-pan balance does she need to make to convince the coach that she knows which coins are which?

### Five Questionable Coins

Ethan is holding a true coin and is told that among five identical looking coins on the table, one is counterfeit. The counterfeit is heavier or lighter than a true coin.

How can he find the counterfeit in two weighings using a simple two-pan balance?

## Solutions to week 107

The answer for Ten from Two involves thinking outside the box (or more properly, thinking outside the star; see below). The answer for Triangular Boundary is 18.