NIELIT Scientist B 2020 November: 6

Question

A solid cube of each side $8\;cm$, has been painted red, blue and black on pairs of opposite faces. It is then cut into cubical blocks of each side $2\:cm$. How many cubes have no face painted?

• A. $0$
• B. $4$
• C. $8$
• D. $12$

Answer 1

OPTION(C)

Total no of blocks = (8/2)×((8/2)×(8/2)= 64

Three coloured blocks = corner blocks = 8

Two coloured blocks (red+blue)= 8

Two coloured blocks (red+black)= 8

Two coloured blocks (blue black) =8

Only red = 8, only black= 8, only blue = 8

No coloured blocks = 8

Total 8+8+8+8+8+8+8+8= 64 

we can easily visualize from diagram also :)