Grandfather's Breakfast*
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I was wondering if you can help me solve this puzzle:

Grandfather is a very hard-boiled customer. In fact, his eggs must be boiled for exactly 15 minutes, no more, no less. One day he asks you to prepare breakfast for him, and the only timepieces in the house are two hourglasses. The larger hourglass takes 11 minutes for all the sand to descend; the smaller takes 7 minutes. What do you do? ...Grandfather grows impatient...

Corrine

* This puzzle is derived from the old class of puzzles with measuring some value using several other constant values like different weights, barrels, cups, etc., and is one of several known versions with hourglasses.

 Mini-Contest 3 - Grandfather's Breakfast is FINISHED

 It was our third mini-contest. Now we have the first six correct answers and propose this contest's results and some details about the puzzle and its solution. With this Mini-Contest 3 is finished.

 Contest Results

 The winners are: 1. Jensen Lai. 2. Hüsnü Sincar. 3. KT - "ktendall". 4. Tamie D. 5. Jane Average. 6. Nicole Takahashi. 7. Matt Kaspar. We've got an almost correct solution from Sandra Payne, but she did say nothing about the moment when to put the eggs into the boiling water. See details at the solution page. Also we've got a correct solution from Matt Kaspar before our Mini-Contest 3 was finished, but accidentally his message was put into a folder with another contest, so when we posted the results and the names of the first six correct solvers his name wasn't included. Our apology. We add his name to the winners list.

 Posted: February 2, 2002  |  Last Updated: July 31, 2007