Von-Strange Returns

 
Professor Von-Strange has another of his weird and wacky ideas; he wants to implant a second pair of eyes on to the back of all human heads.

Fortunately at this time he has no real humans to experiment on - only mannequins.

Von-Strange has been collecting glass eyes for this experiment and now has 3 green, 3 blue and 3 brown eyes. These are placed in a machine that will dispense one out at random at the press of a button.

How many times will Von-Strange have to press the button to be sure he has three pairs of matching eyes, if he doesn't check the colours as they are dispensed?
 

Answer


































 

8 times

 

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