Question 89

Logical Reasoning Cube And Dices Easy

How many minimum number of colors will be required to paint all the sides of a cube without the adjacent sides having the same colors ?

(A) 3
(B) 4
(C) 5
(D) 6
✓ Correct Answer: Option A Verified Solution

📘 Step-by-Step Solution & Detailed Explanation:

Logical Analysis

The problem asks for the minimum number of colors needed to paint a cube's six faces such that no two adjacent faces share the same color. Faces that share an edge are considered adjacent, while faces on opposite sides are not.

Step-by-Step Coloring Process

We can solve this by attempting to color the cube with the smallest number of colors possible.

  1. Start with one face: Let's paint the top face with Color 1.
  2. Color the adjacent faces: The top face is adjacent to four other faces (front, back, left, and right). None of these four can be Color 1.
  3. Introduce a second color: Let's paint the front face with Color 2.
  4. Introduce a third color: Now consider the left face. It is adjacent to both the top (Color 1) and the front (Color 2). Therefore, it cannot be Color 1 or Color 2. We must use a new color, Color 3.
  5. Reuse existing colors: Now that we have three colors, let's see if we can finish painting the cube without introducing a fourth.
    • The right face is adjacent to the top (Color 1) and front (Color 2), but it is opposite the left face (Color 3). We can reuse Color 3 for the right face.
    • The back face is adjacent to the top (Color 1) and the left/right faces (Color 3), but it is opposite the front face (Color 2). We can reuse Color 2 for the back face.
    • The bottom face is adjacent to all four side faces (Colors 2 and 3), but it is opposite the top face (Color 1). We can reuse Color 1 for the bottom face.

Final Coloring Scheme

We have successfully colored the entire cube using only three colors:

  • Color 1: Top and Bottom faces
  • Color 2: Front and Back faces
  • Color 3: Left and Right faces

Since it is impossible to color a cube with only two colors (as a corner has three mutually adjacent faces), the minimum number required is three.

Conclusion

The minimum number of colors required is 3.

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