Verbal Reasoning - Cube and Cuboid - Discussion

The following questions are based on the information given below:

  1. A cuboid shaped wooden block has 4 cm length, 3 cm breadth and 5 cm height.
  2. Two sides measuring 5 cm x 4 cm are coloured in red.
  3. Two faces measuring 4 cm x 3 cm are coloured in blue.
  4. Two faces measuring 5 cm x 3 cm are coloured in green.
  5. Now the block is divided into small cubes of side 1 cm each.

2. 

How many small cubes will have only one face coloured ?

[A]. 12
[B]. 28
[C]. 22
[D]. 16

Answer: Option C

Explanation:

2 from the front + 2 from the back + 3 from the left + 3 from the right + 6 from the top + 6 from the bottom = 22


Santhosh said: (Jan 1, 2012)  
But according to l*2 + b*2 + h*2 =24???

Lalit Ku Sahu said: (May 27, 2014)  
For cube:

One face coloured= 6*(n-2)^2.
= 6*(n-2)*(n-2).

Similarly for CUBOID (4*3*5):

One face coloured = 2*(L-2)*(B-2)+2*(B-2)*(H-2)+2*(H-2)*(L-2).

=2*(4-2)*(3-2)+2*(3-2)*(5-2)+2*(5-2)*(4-2).

= 2*2*1 + 2*1*3 + 2*3*2.

= 4 + 6 + 12.

= 22 ANSWER.

Mohit said: (Aug 1, 2020)  
@Lalit.

Why you subtracting 2?

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