Logic Puzzle

Illkillya

OK, this one is another non-tricky, straight-forward one, easier than the glasses:

You have to boil a single egg for exactly nine minutes.

All you have are two hourglasses, able to precisely measure in sand seven and four minutes, respectively.

How can you boil the egg correctly, using only these 2 hour glasses?
(pretend you waste no time in flipping, and stuff)

Paladin

Ez
start them together.
When the four ends flip it. Start ure egg. There is 3 left in the 7. The 3 runs and u flip the 4 starting it again. When the 7 is gone there is also 3 gon in the four. Flip both of em agin. When the 3 runs out on the four, there will be 3 after running into the 7. Flip the 7 and allow the 3 minutes of sand to run. And voila! 9 minutes

Illkillya

the puzzle was unsolved for 13 minutes, that was just a warm-up.....

Paladin

Or as me sis jus pointed out...
Start the 2 timers. When the 4 runs there is 3 in the seven. flip the 4 and allow the 7 timer to run. When that 3 is gone there is still 1 min to run in the 4 timer. Start yer egg now. When that 1 in the four runs out, flip it and allow it to run completely twice, two 4 minute runs making 4 + 4+ the 1 at the start.

the celtic tiger

Here's my way....start the two timers.....set the timer on the cooker for nine minutes exactly....put on the egg. Keep flipping the timers and voila! NINE MINUTES EXACTLY!

tct