Direction : A cube is divided into 343 identical cubelets. Each cut is...
Cubelets located at the corners of the cube:
- Each corner cubelet is part of three adjacent faces, so it will be colored with all three colors (green, red, and blue).
- There are 8 corner cubelets in total
Direction : A cube is divided into 343 identical cubelets. Each cut is...
Solution:
Given, a cube is divided into 343 identical cubelets and colored with green, red and blue on three sets of adjacent faces.
To find: Number of cubelets which are colored exactly three colors.
Approach:
- The cube has 6 faces and each face is adjacent to two other faces.
- Hence, each set of adjacent faces has 2 faces of the same color and 1 face of a different color.
- A cubelet can be colored with exactly 3 colors only if it is located at a corner of the cube.
Explanation:
- Number of corners in a cube = 8 (where 3 edges meet).
- Each corner cubelet is colored with 3 colors.
- The colors of each corner cubelet can be arranged in 3! ways (since there are 3 colors, i.e., green, red, and blue).
- Total number of corner cubelets = 8
- Therefore, the total number of cubelets which are colored exactly three colors = 8 x 3! = 48
- But each cubelet is counted 3 times (once for each set of adjacent faces), so we need to divide by 3.
- Hence, the required number of cubelets = 48/3 = 16.
- But, the cubelets at the corners of the cube which are colored with 3 colors are common to two sets of adjacent faces, so we need to divide by 2.
- Hence, the final answer = 16/2 = 8.
Therefore, the correct answer is option (C) 2.