SOLUTION FOR NINE MARBLES:

Place 3 marbles on each tray.
- If the first weighing doesn't balance, remove all the marbles from the lighter side, and place one marble on each tray from the heavier tray.  The heavier side is the 1.1 ounce marble, but if they balance, then the marble from the heavier tray from the first weighing that was not weighed in the second weighing is the heavier one(1.1).

- If the marbles balance on the first weighing, remove the marbles from the trays, and place 2 of the remaining marbles not yet weighed on the trays, one on each tray.  If one is heavier, it is the heavier marble(1.1), but if they balance, the remaining marble not weighed is the heavier one.
 

 

    

 

 

 

 

 

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