(1).

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The function is $\"\"$ .

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The average cost for box: $\"\"$

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Differentiate with respect to x.

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$\"\"$

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For minimize average cost, $\"\"$ .

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$\"\"$

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$\"\"$

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$\"\"$

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$\"\"$

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$\"\"$ .

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The number of the boxes is 2,200.

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(b).

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Find the resulting average cost for x boxes.

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Substitute x = 2,200 in the equation $\"\"$

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$\"\"$

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$\"\"$