Question

Marla has a large white cube that has an edge of 10 feet. She also has enough green paint to cover 300 square feet. Marla uses all the paint to create a white square centered on each face, surrounded by a green border. What is the area of one of the white squares, in square feet?

$5\sqrt2$

$10$

$10\sqrt2$

$50$

$50\sqrt2$

Video solution:

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Written solution:

The total surface area is $6\cdot 10\cdot 10 = 600.$ Therefore, $600-300 = 300$ square feet aren't covered. This would be $\dfrac{300}{6} = 50$ square feet per face.

Thus, the answer is D .

2012 AMC 8 Problem 21

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Problem 21 in Other Years