Archive for November 2005

Here’s a neat one

A farmer has one rock weighing 40 pounds. Using a balance scale and this rock, he can measure 40 pound units of wheat, which he sells at the market. One day, his neighbor comes by and borrows the rock. After a few days, the neighbor returns and tells the farmer that he has some bad news and some good news.
The bad news is that he dropped the 40 pound rock and it broke into four pieces. The good news, he says, is that the farmer can now use these four fragments to measure any amount from 1 to 40 pounds, to an accuracy of one pound, by using the balance scale once. How much does each rock fragment weigh?