Direction: 125 cubes of similar size are arranged in the form of the bigger cube (5 cubes on each side, i.e., 5 x 5 x 5) All the small cubes lying on the edge of the top layer of the bigger cube are removed and also cubes lying at the four corners of the bottom face are removed. All exposed faces of the block thus left are coloured red.
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How many cubes are with two faces painted?
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- 20
- 24
- 18
- 16
Correct Option: B
Number of cubes with two face painted from the top side (Which is a square of 3 x 3 = 9 cubes ) is 4.
Number of cubes with two face painted from the 2nd from top side (Which has four edges and edge has 3 such cubes) is 4 x 3 = 12.
Number of such cubes from vertical edges is 4 x 1 = 4
Number of such cubes from bottom face is 4 x 1 = 4
Hence total such cubes is 4 + 12 + 4 + 4 = 24
