Verbal Reasoning - Cube and Cuboid - Discussion

The following questions are based on the information given below:

  1. All the faces of cubes are painted with red colour.
  2. The cubes is cut into 64 equal small cubes.

4. 

How many small cubes are there whose two adjacent faces are coloured red ?

[A]. 0
[B]. 8
[C]. 16
[D]. 24

Answer: Option D

Explanation:

Number of small cubes having two adjacent faces coloured red = (x - 2) x No. of edges

= (4 - 2) x 12

= 24


Pratheebha said: (Aug 14, 2011)  
I couldn't understand this question.

Bhavna Tayenjam said: (Nov 18, 2013)  
My opinion:

The two middle cubes in every edges should be counted i.e. a total of 8 middle cubes at the edges.

The cubes located at the 4 vertices of the cubes must also be counted even though they have 3 faces colored red. It still has its two adjacent faces colored.

So taking into account of these facts, the total small cubes having two adjacent faces colored red = 24+8.

Sanchita Roy said: (Nov 30, 2014)  
The answer is correct but the method. I m not sure about it because the question is about adjacent faces.

So the side of each edge is 4 units and the adjacent faces on the edges is red consisting 4 cubes of 1 cubic unit. The no of faces are 6.

Multiplying no of cubes of each edge to the total no of faces gives the no of cubes having two ADJACENT faces colored red I. E, 4*6=24.

Hari Krishna said: (Oct 10, 2016)  
In the question he asked two adjacent faces are coloured red, not at least two adjacent faces are coloured red, so we will count the cubes with sides coloured, in my opinion, this is definitely wrong.

The actual answer is 16.

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