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u2lover
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XxxyyY
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game over
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MA
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u2lover
A large cube 10 cm on a side is composed of cubes 1 cm on a side. The outside of the large cube is painted red and then all of the individual cubes are mixed in a drum. If one cube is selected randomly, which of the following is the approximate probability that the cube will have at least one red face?

A) 1:6
B) 1:5
C) 1:4
D) 1:3
E) 1:2

again... fastest way to solve this :?:


totoal = 10^3 = 1000
small inside cubs that are not painted = 8^3=512
so the prob = (1000-512)/1000 = 488/1000 i.e approx 1:2.
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yep. (E) it is.
same methods as used by MA and gameover.
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Sorry for posting links here..

https://www.gmatclub.com/phpbb/viewtopic ... light=drum

P(atleast one red face) = 1 - P(no red face)

The unpainted "area of the cube" is 8*8*8

the total area = 10* 10*10

P(No reds) = 512/1000

P(atleast one red face) = 488/1000

Approximately 1:2


Another one:
https://www.gmatclub.com/phpbb/viewtopic ... light=drum
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OA is E as seen in the other thred
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u2lover
A large cube 10 cm on a side is composed of cubes 1 cm on a side. The outside of the large cube is painted red and then all of the individual cubes are mixed in a drum. If one cube is selected randomly, which of the following is the approximate probability that the cube will have at least one red face?

A) 1:6

B) 1:5

C) 1:4

D) 1:3

E) 1:2

again... fastest way to solve this :?:


E it can only be :)



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