Gabriele, the lover of cubes, has bought a magnificent collector's item: a cube made entirely of chocolate, having edges of length 10cm. Unfortunately, having lost a bet with two of his friends, he will have to give up two thirds of the volume of the chocolate block. Gabriele has decided to take as his own portion of chocolate a smaller cube, having one of its vertices coinciding with one of the vertices of the purchased cube and its faces parallel to those of the purchased cube. In the end, he gives his two friends the remaining chocolate. Let us denote by S the total surface area of the chocolate block given away, expressed in cm2. Then we have...
Pick one
Solution
Solution:
The answer is (D). The chocolate block given away has the same surface area as the original cube, equal to 6⋅102cm2. Indeed, when the smaller cube is cut away, 3 of its faces are exactly equal to the 3 squares that form on the chocolate block given away.
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Source: MathNet,
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