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  From Jennifer, age 14 of MD:

You want to cook an egg for exactly 15 minutes and you only have an 11 minute egg timer and a 7 minute egg timer. How can you cook an egg for exactly 15 minutes, with no other timing device and without stopping and starting the cooking process?

Answer below...

 
 
   

To reveal the answer, click and drag your mouse between the lines:

 Turn the 2 timers over at the same time and when the 7  
 minute timer runs out, start cooking the egg.  
 You have exactly 4 mins left on the 11 minute timer.  
 When that timer runs out, flip it back over and cook the egg for another 11  
 minutes. Now you have an egg that cooked for exactly 15  
 minutes!  

not yet implemented