Answer to May 20, 2002 Problem
by Karl Fulves

Hard Boiled

 
With a 7-minute hourglass and an 11-minute hourglass, what is the quickest way to time the boiling of an egg for 15 minutes?

 

Solution to Problem:

There are several ways to boil the egg with the two timers but the quickest is 15 minutes.

To do this, turn over both timers and start boiling the egg.
When the 7-minute timer is finished, turn it over.
When the 11-minute timer is done, four minutes worth of sand has drained from the 7-minute timer.
So, turn over the 7-minute timer.
When the 7-minute timer is finished, 15 minutes will have elapsed, so take the egg off the stove.


Correctly solved by:

1. Kelsey Dufendach Rockford, Michigan
2. Walt Arrison Philadelphia, Pennsylvania
3. David L. Stark Winchester, Virginia
4. Keath Mealy Cincinnati, Ohio
5. Nate Troup Arlington, Virginia
6. Rick Jones Kennett Square, Pennsylvania
7. Geoff Keith Santa Monica, California
8. David Powell Winchester, Virginia
9. John Funk Ventura, California
10. Bill Hall Wellington, Florida
11. James Alarie University of Michigan -- Flint, Michigan
12. David and Judy Dixon Bennettsville, South Carolina