Problem:
Square corners, units on a side, are removed from a unit by unit rectangular sheet of cardboard. The sides are then folded to form an open box. The surface area, in square units, of the interior of the box is
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Answer Choices:
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Solution:
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The interior (or exterior) has the same surface area as one side of the sheet of cardboard after the corners have been removed. The area of the sheet is and the area of each of the square corners removed is , so the answer is .
Answer: .
The problems on this page are the property of the MAA's American Mathematics Competitions