Boiling Eggs - The Answer

(Solution Hidden)


1. Start boiling the eggs and flip over both hourglasses.

2. When the 4 minute hourglass finishes, flip it over.

3. When the 7 minute hourglass finishes, flip it over.

4. When the 4 minute hourglass finishes for a second time, then eight minutes have elapsed, and the 7 minute hourglass has one minute of sand on the other side.

5. Flip over the 7 minute hourglass so it counts down the 9th minute.