Make 3 groups of 3 boxes

Group 1:

Box 1, 2, and 3

Group 2:

Box 4, 5, and 6

Group 3:

Box 7, 8, and 9

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1st use of Balance Equipment:

Weigh Group 1 and Group 2

Scenario A:

Group 1 weighs less than Group 2. Group 1 has the lighter box.

Scenario B:

Group 2 weighs less than Group 1. Group 2 has the lighter box.

Scenario C:

Group 1 weighs the same as Group 2. Conclusion, Group 3 contains the lighter box.

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2nd use of Balance Equipment:

Taking the Group you know to have the light box in it, there are 3 boxes left. Place one box on one side of the scale, a different box on the other side of the scale, and the third box, leave off to the side.

Scenario A:

One of the boxes on the scales weighs less than the other. Conclusion, you have discovered the lighter box.

Scenario B:

Both boxes on the scales weigh the same. Conclusion, the box you put off to the side is the lighter box.

SOLVED – CASE CLOSED 🙂