Bunuel wrote:

A solid cube of side 6 is first painted pink and then cut into smaller cubes of side 2. How many of the smaller cubes have paint on exactly 2 sides?

A. 30

B. 24

C. 12

D. 8

E. 6

Hi,

the point that will be helpful always -

1) the corner cube of any BIGGER cube will have 3 faces open to air ..

2) All cubes in edges except the corner will have 2 faces outwards..

3)rest all that are vis outside will have 1 face outwards...

lets solve the Q now-

Bigger cube side is 6..

smaller cube side is 2..

so EACH edge is cut into 6/2 = 3 pieces..

Now lets apply here-

1) corner ubes - 8 - will have 3 face painted..

2) cubes in each edge = 3, out of which 2 are corner ones....

so ONE cube in each edge has two faces painted..

number of edges = 12, so number of cubes = 12*1 =12

3) Cubes with single edge painted = Total - (1) -(2)

But we are looking for 2 faces ..

ans 12

C

_________________

1) Absolute modulus : http://gmatclub.com/forum/absolute-modulus-a-better-understanding-210849.html#p1622372

2)Combination of similar and dissimilar things : http://gmatclub.com/forum/topic215915.html

3) effects of arithmetic operations : https://gmatclub.com/forum/effects-of-arithmetic-operations-on-fractions-269413.html

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