You have to boil a single egg for exactly nine minutes.
All you have are two hourglasses, able to measure (in sand) seven and four minutes, respectively.
How quickly, using only these two hourglasses, can you boil an egg?
(In reply to
SOLUTION FOR EGGALICIOUS by christopher hii)
you all are over complicating this problem.
Start by turning both of the timers over, and place the egg in the water.
when the four minute timer runs out flip it back over.
at this point you will know that their are 3 minutes left on the 7 min timer.
When the 7 min timer runs out filp it back over and let it run unitl the 4 min timer runs out which you know it will have ran for 1 min total. Thus adding 1 minute to the 7 min timer. Even thoug the 7 min timer has not finished you still know that it has 1 min worth of sand in the bottom. Flip it back when the 4 min timer finishes and when this timer runs out your 9 minutes are up, and you finished in only 9 minutes, not 16.
The correct solution
