Official Solution
DS12402.01
It is given that the volume of the top cube in the stack is 8 cubic centimeters, from which it follows that the top block has edges of length 2 cm, but no information is given about the size of the other blocks in the stack or how many blocks the stack contains; NOT sufficient.
It is given that the height of the stack of blocks is 10 cm, but no information is given about the size of any of the blocks in the stack or how many blocks are in the stack.
Taking (1) and (2) together gives no information about the size of the blocks below the top block or how many blocks are in the stack. For example, there could be two blocks with edges of lengths 2 cm and 8 cm. The volume of the top block would be 8 cubic centimeters, the height of the stack would be 10 cm, and the volume of the stack of blocks would be 520 cubic centimeters. But there could also be three blocks with edges of lengths 2 cm, 3 cm, and 5 cm. The volume of the top block would be 8 cubic centimeters, the height of the stack would be 10 cm, and the volume of the stack of blocks would be 160 cubic centimeters.
Both statements together are still not sufficient.
Tip: Do not assume anything that is not explicitly stated in the problem. In this problem, it is tempting to assume that all of the blocks are identical, in which case there would be five blocks, each with height 2 cm to give the whole stack a height of 10 cm and a volume of 40 cubic centimeters. Under the assumption that all of the blocks are identical, the correct answer would be C.
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